Perovskite thin film and preparation method thereof, solar cell

Abstract

This invention provides a perovskite thin film, its preparation method, and a solar cell. The perovskite thin film is prepared by the following method: forming an inorganic salt thin film layer to obtain a first intermediate; forming a phosphate derivative layer on the inorganic salt film of the first intermediate to obtain a second intermediate; coating the surface of the phosphate derivative layer of the second intermediate with an organic salt solution, and performing a first annealing treatment to obtain the perovskite thin film; the phosphate derivative layer includes at least one of 2PACz, MeO-2PACz, and phosphocholine. The perovskite thin film preparation method provided by this invention uses a phosphate derivative to form coordination bonds with uncoordinated lead ions in the perovskite, filling vacancy defects, reducing the formation of defects during perovskite crystallization, and improving the film quality. Therefore, when the perovskite thin film is used in a battery, it can improve the electrical performance of perovskite solar cells.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a perovskite thin film, its preparation method, and a solar cell. Background Technology

[0002] Perovskite solar cells have attracted considerable attention from researchers both domestically and internationally due to their advantages such as high absorption coefficient, high carrier mobility, low exciton binding energy, and ability to be fabricated at low temperatures using solution methods. In just a few decades, their photoelectric conversion efficiency has increased from 3.8% to 26.7%, comparable to crystalline silicon solar cells. However, the performance of perovskite solar cells is significantly affected by the quality of the perovskite thin film. Currently, most high-efficiency devices use perovskite thin films prepared using solution methods. Since perovskite is a crystalline material, its ionic properties inevitably lead to defects during crystallization. These defects cause non-radiative recombination of photogenerated carriers, resulting in charge loss and impacting device performance. Furthermore, perovskite materials exhibit significant ionic characteristics and are prone to ion migration, which can disrupt the perovskite crystal structure, severely affecting device performance and stability.

[0003] Defect passivation is an effective strategy for improving the performance and stability of perovskite solar cells, and Lewis bases are effective passivating agents for improving the quality of perovskite thin films. Researchers often use molecules with Lewis base groups to passivate perovskite buried interfaces and surface defects; however, this method has limited passivation effect. In addition, conventionally adding them as additives to precursor solutions can affect charge transport and PbI2 crystallization.

[0004] The performance and stability of perovskite solar cells are limited by the quality of the perovskite thin film, and the key to improving the quality of perovskite thin films lies in reducing defects and suppressing ion migration. Conventional methods to improve film quality by passivating the perovskite buried interface and surface defects have limited effectiveness, while directly adding additives to the precursor can affect charge transport and PbI2 crystallization.

[0005] Therefore, developing a method to effectively improve the electrical properties of perovskite thin films has become a research direction in this field. Summary of the Invention

[0006] This invention provides a method for preparing perovskite thin films, which has the advantage of producing perovskite thin films with good electrical properties.

[0007] The present invention also provides a perovskite thin film, which has good electrical properties.

[0008] This invention provides a solar cell with good electrical performance.

[0009] The present invention also provides a method for preparing a solar cell, which has the characteristic of producing perovskite solar cells with good electrical performance.

[0010] This invention provides a method for preparing perovskite thin films, comprising the following steps:

[0011] An inorganic salt thin film layer is formed to obtain the first intermediate;

[0012] A phosphate derivative layer is formed on the inorganic salt film of the first intermediate to obtain the second intermediate;

[0013] An organic salt solution is coated on the surface of the phosphate derivative layer of the second intermediate, and a first annealing treatment is performed to obtain the perovskite film.

[0014] The phosphate derivative layer includes at least one of 2PACz, MeO-2PACz, and phosphocholine.

[0015] In the method described above, the inorganic salt thin film layer comprises PbI2.

[0016] In the method described above, the organic salt solution includes FAI and MACl.

[0017] In the method described above, the concentration of FAI in the organic salt solution is 60-100 mg / mL; and / or the concentration of MACl is 5-20 mg / mL.

[0018] The method described above, wherein forming a phosphoric acid derivative layer on the inorganic salt film of the first intermediate specifically includes coating the surface of the inorganic salt film with a phosphorus source solution;

[0019] The phosphorus source solution includes the phosphoric acid derivative;

[0020] The method of coating the phosphorus source solution is selected from at least one of slot coating, doctor blade coating, spraying, spin coating and screen printing.

[0021] In the method described above, the phosphorus source solution comprises a phosphoric acid derivative and a solvent, wherein the solvent comprises isopropanol, and the concentration of the phosphoric acid derivative is 1-3 mg / mL.

[0022] The present invention also provides a perovskite thin film, comprising an inorganic salt film layer, a phosphate derivative layer and an organic salt layer stacked sequentially.

[0023] The perovskite thin film as described above, wherein the phosphate derivative layer comprises at least one of 2PACz, MeO-2PACz, and phosphocholine;

[0024] The inorganic salt thin film layer includes PbI2.

[0025] The present invention also provides a solar cell comprising any of the above-mentioned perovskite thin films.

[0026] The present invention also provides a method for preparing a solar cell, comprising the following steps:

[0027] A hole transport layer, a buried interface passivation layer, a perovskite thin film, a top interface passivation layer, an electron transport layer, a buffer layer, and a metal electrode are sequentially formed on one side surface of a transparent conductive substrate to obtain the solar cell.

[0028] The perovskite film comprises an inorganic salt film layer, a phosphate derivative layer, and an organic salt layer stacked sequentially; the buried interface passivation layer and the top interface passivation layer comprise passivating agents;

[0029] The passivating agent is selected from at least one of PEAI, phosphocholine, and ammonium thiocyanate.

[0030] The method for preparing perovskite thin films provided by this invention uses phosphate derivatives to form coordination bonds with uncoordinated lead ions in perovskite, filling vacancy defects, reducing the formation of defects during perovskite crystallization, and improving film quality. As a result, the perovskite thin film prepared can improve the electrical performance of perovskite solar cells when used in batteries. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0032] Figure 1 The structural formula of phosphoric acid choline used in Example 1;

[0033] Figure 2 The structural formula of 2PACz used in Example 2;

[0034] Figure 3 The structural formula of MeO-2PACz used in Example 3;

[0035] Figure 4 JV diagrams of the batteries prepared for each embodiment and comparative example;

[0036] Figure 5 SEM image of the battery obtained in Example 1;

[0037] Figure 6 SEM images of the batteries obtained for Comparative Example 1;

[0038] Figure 7 SEM images of the batteries obtained for Comparative Example 2;

[0039] Figure 8This is a structural diagram of the battery prepared in Example 1;

[0040] Figure 9 The diagram shows the structure of the battery prepared in Comparative Example 1.

[0041] Explanation of reference numerals in the attached figures:

[0042] 10-Hole transport layer;

[0043] 20 - Buried interface passivation layer;

[0044] 30a-Inorganic salt thin film layer;

[0045] 30β-phosphate derivative layer;

[0046] 30c - Organic salt layer;

[0047] 40 - Top interface passivation layer;

[0048] 50 - Electron transport layer;

[0049] 60-Buffer layer;

[0050] 70 - Metal electrode.

[0051] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The described embodiments are some, but not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0053] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0054] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0055] The terms “first,” “second,” and “third” (if any) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0056] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or display that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or display.

[0057] In existing technologies, the ionic properties of perovskite crystals inevitably lead to defects during crystallization. These defects cause nonradiative recombination of photogenerated carriers, resulting in charge loss and impacting device performance. Furthermore, perovskite materials exhibit significant ionic characteristics and are prone to ion migration, which disrupts the perovskite crystal structure and severely affects device performance and stability. Therefore, introducing new materials to passivate these defects could solve these technical problems.

[0058] The first aspect of this invention provides a method for preparing a perovskite thin film, the method comprising the following steps:

[0059] An inorganic salt film is formed to obtain the first intermediate;

[0060] A phosphate derivative layer is formed on the inorganic salt film of the first intermediate to obtain the second intermediate;

[0061] An organic salt solution was coated on the surface of the phosphate derivative layer of the second intermediate, and a first annealing treatment was performed to obtain a perovskite film.

[0062] The phosphate derivative layer includes at least one of 2PACz, MeO-2PACz, and phosphocholine.

[0063] To facilitate the formation of inorganic salt films, in one embodiment, the inorganic salt film can be formed on the surface of a substrate. The present invention does not limit the specific selection of the substrate, as long as it meets the requirements for forming perovskite films. In one embodiment, the substrate may be selected from at least one of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), indium zinc oxide (IZO), and aluminum zinc oxide (AZO).

[0064] Inorganic salt films include inorganic salts. This invention does not limit the specific selection of inorganic salts and may use commonly used inorganic salts in the art for forming perovskite films. For example, at least one of lead halide salts and cesium halide salts, such as at least one of PbI2, PbCl2, and CsBr.

[0065] This invention does not limit the formation method of the inorganic salt film, and methods commonly used in the art can be used. For example, in one embodiment, the inorganic salt can be dissolved in a solvent to obtain a precursor solution, which is then dropped onto the surface of a substrate and subjected to spin coating and annealing to obtain the inorganic salt film. Alternatively, slot coating or vacuum evaporation can be used instead of spin coating.

[0066] Subsequently, a phosphate derivative layer is formed on the inorganic salt film of the first intermediate to obtain the second intermediate. The phosphate derivative is an organic compound containing phosphorus phosphate groups, and the acid derivative layer includes at least one of 2PACz, MeO-2PACz, and phosphocholine. Specifically, 2PACz is [2-(9H-carbazole-9-yl)ethyl]phosphonic acid, and MeO-2PACz is [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid.

[0067] The present invention does not limit the method of forming the phosphate derivative layer, and the phosphate derivative layer can be formed by means commonly used in the art.

[0068] Subsequently, an organic salt solution is coated onto the surface of the phosphate derivative layer of the second intermediate, followed by a first annealing treatment to obtain a perovskite film. The organic salt solution comprises an organic salt and a solvent. This invention does not limit the specific type of organic salt; common organic salts in the art can be used, as long as they meet the requirement of forming a perovskite film after annealing with the inorganic salt film. In one embodiment, the organic salt can be selected from at least one of FAI and MACl. FAI is formamidinium hydroiodate, and MACl is methylamine hydrochloride. Furthermore, the coating process with the organic salt solution can be achieved by spin coating or slot coating.

[0069] The first annealing treatment allows the inorganic salts in the inorganic salt film to react with the organic salts, resulting in a perovskite film. This invention does not limit the processing conditions of the first annealing treatment; common annealing conditions in the art can be used. The final perovskite film obtained is a product obtained after the first annealing treatment of a layered structure comprising an inorganic salt film, a phosphate derivative layer, and an organic salt solution.

[0070] The inventors have discovered that perovskite films prepared using the method provided in the first aspect of this invention, when applied to perovskite solar cells, can significantly improve the electrical performance of the cells. The inventors speculate that this is because the phosphate groups in the phosphate derivative layer can act as Lewis bases to form coordination bonds with uncoordinated lead ions in the perovskite, thereby reducing defect formation, improving film quality, and enhancing the performance and stability of the perovskite solar cell. Specifically, after adding an additional phosphate derivative layer to the surface of the inorganic salt film, the phosphate derivative layer not only does not affect the dense crystallization process and charge transport of the inorganic salt film, but also acts as a buffer layer for perovskite crystallization, delaying the interaction between the organic and inorganic salt films, thus contributing to a more uniform perovskite film, extending carrier lifetime, and increasing charge transport. Furthermore, the phosphate groups in the phosphate derivatives contain unbonded electron pairs, which can form coordinate bonds with uncoordinated lead ions in the perovskite, filling vacancies and reducing the formation of defects during perovskite crystallization, thus improving film quality and reducing nonradiative recombination of charge carriers. As a result, when the perovskite film is used in perovskite solar cells, it can improve the electrical performance of perovskite solar cells, specifically in terms of photoelectric conversion efficiency and long-term stability.

[0071] In one embodiment, the inorganic salt film includes PbI2. The perovskite film prepared from the PbI2-containing inorganic salt film can bring better electrical performance to perovskite solar cells. This invention does not limit the formation method of this inorganic salt film. In one embodiment, PbI2 can be dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide to obtain a precursor solution. This precursor solution is then dropped onto the surface of a substrate and subjected to spin-coating and annealing to obtain the inorganic salt film. In the precursor solution, the PbI2 concentration is 600-800 mg / L, and the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is (5-10):1.

[0072] Furthermore, in another embodiment, the organic salt solution includes FAI, MACl, and isopropanol. The concentration of FAI in the organic salt solution is 60-100 mg / mL; the concentration of MACl in the organic salt solution is 5-20 mg / mL. This ratio of organic salt solution can further improve the quality of the perovskite thin film.

[0073] In one embodiment, forming a phosphate derivative layer on an inorganic salt film of the first intermediate specifically includes coating the surface of the inorganic salt film with a phosphorus source solution comprising the phosphate derivative. The method for coating the phosphorus source solution is selected from at least one of slot coating, doctor blade coating, spraying, spin coating, and screen printing. More preferably, the method for coating the phosphorus source solution is spin coating, wherein the spin coating speed is 4000 rpm and the spin coating time is 30 s.

[0074] Furthermore, the phosphorus source solution includes a phosphoric acid derivative and a solvent, the solvent being isopropanol, and the concentration of the phosphoric acid derivative in the solution is 1-3 mg / mL.

[0075] To ensure better electrical performance of the prepared perovskite thin film when used in batteries, the temperature of the first annealing treatment can be controlled at 135-150℃, and the treatment time at 15-35 min. Appropriate annealing temperature and time allow for suitable reaction temperatures and durations between the inorganic salt film, the phosphate derivative layer, and the organic salt, thereby improving the performance of the perovskite thin film.

[0076] A second aspect of the present invention provides a perovskite thin film comprising an inorganic salt film layer, a phosphate derivative layer, and an organic salt layer stacked sequentially. The inorganic salt film layer and the phosphate derivative layer have the same composition as described above, and the organic salt layer includes FAI and MACl. Specifically, the sequential stacking means that one surface of the phosphate derivative layer is in contact with the inorganic salt film layer, and the other surface of the phosphate derivative layer is in contact with the organic salt layer.

[0077] This invention does not limit the preparation method of the perovskite thin film described above. In one embodiment, the perovskite thin film is prepared using the preparation method of the perovskite thin film provided in the first aspect of this invention. The perovskite thin film provided by this invention has the characteristic of good electrical properties.

[0078] In one embodiment, the phosphate derivative layer includes at least one selected from 2PACz, MeO-2PACz, and phosphocholine; the inorganic salt film layer includes PbI2. Perovskite films possessing the above properties exhibit superior electrical performance.

[0079] A third aspect of this invention provides a solar cell comprising a perovskite thin film prepared by the method for preparing the perovskite thin film provided in the first aspect of this invention. This invention does not limit the specific structure of the perovskite thin film battery; structures commonly used in the art can be used. For example, in one embodiment, the perovskite solar cell comprises, in sequence, a transparent conductive substrate, a hole transport layer, a buried interface passivation layer, a perovskite thin film, a top interface passivation layer, an electron transport layer, a buffer layer, and a metal electrode. As another example, in another embodiment, the perovskite solar cell comprises, in sequence, a transparent conductive substrate, an electron transport layer, a buried interface passivation layer, a perovskite thin film, a top interface passivation layer, a hole transport layer, a buffer layer, and a metal electrode.

[0080] A fourth aspect of the present invention provides a method for preparing a solar cell, the method comprising the following steps:

[0081] A hole transport layer, a buried interface passivation layer, a perovskite thin film, a top interface passivation layer, an electron transport layer, a buffer layer, and a metal electrode are sequentially formed on one side surface of a transparent conductive substrate to obtain a solar cell.

[0082] The perovskite thin film was prepared using the perovskite thin film preparation method provided in the first aspect of the present invention.

[0083] Specifically, the preparation method of the above-mentioned perovskite solar cell includes the following process:

[0084] A hole transport layer is prepared on a transparent conductive substrate, and then a PbI2 thin film is prepared and annealed on the hole transport layer using a precursor solution. Next, a phosphate derivative is introduced onto the surface of the PbI2 thin film, and then an ammonium salt is used for precursor conversion to form a perovskite thin film. Subsequently, PEAI is spin-coated for passivation, and then an electron transport layer and a buffer layer are prepared on the surface. Finally, electrodes are deposited by evaporation to obtain a complete perovskite device. The specific steps are as follows:

[0085] 1) The transparent conductive substrate can be one of ITO, FTO or ZTO, and it is cleaned and then treated with UVO.

[0086] 2) A hole transport layer (HTL) is prepared on the transparent conductive substrate in step 1). The hole transport layer can be selected from at least one of PTAA, 2PACz, NiOx, Me-4PACz, MeO-2PACz, and 4PADBC.

[0087] 3) A buried interface passivation layer is formed on the hole transport layer by spin coating.

[0088] 4) Using the perovskite thin film preparation method provided in the first aspect of the present invention, a perovskite thin film is prepared on the surface of the interface passivation layer.

[0089] 5) A top interface passivation layer is formed on the surface of the perovskite film obtained in step 4).

[0090] 6) An electron transport layer and a buffer layer are formed on the surface of the perovskite thin film in step 5) by spin coating or vacuum evaporation, and finally the metal electrode is deposited.

[0091] Furthermore, in step 1) above, the cleaning step of the transparent conductive substrate is to sonicate in cleaning agent, deionized water and isopropanol for 1 hour each; followed by ultraviolet ozone treatment for 3~30 minutes.

[0092] Step 2) specifically includes the following:

[0093] PTAA, 2PACz, Me-4PACz, and NiO were coated at concentrations of 0.5–20 mg / ml onto a transparent conductive substrate after UVO. x Use one of the following: 4PADBC, MeO-2PACz, or a mixture thereof. Spin coating should be performed at a speed between 3000 rpm and 6000 rpm for 30 seconds. After spin coating, place the product on a 100°C hot plate for annealing for 10 minutes.

[0094] In the above scheme, step 4) also includes the following:

[0095] The interface passivation layer was spin-coated at a speed of 6000 rpm for 30 seconds, with a concentration of 1-3 mg / ml, and the solvent was isopropanol or ethanol.

[0096] The PbI2 precursor fluid concentration is 600~800 mg / ml, dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide at a volume ratio of 5~10:1.

[0097] The spin coating speed was 1500 rpm, and the spin coating time was 30 s. The annealing temperature was 50~70℃, and the annealing time was 1 min.

[0098] In the above scheme, step 5) specifically includes the following:

[0099] The phosphate derivative can be one of 2PACz, MeO-2PACz, or phosphocholine, at a concentration of 1.5 mg / mL, using isopropanol as the solvent. Spin coating is performed in a glove box at a speed of 4000 rpm for 30 seconds. The phosphate group can act as a Lewis base to form coordination bonds with uncoordinated lead ions in the perovskite, thereby reducing defect formation, improving film quality, and enhancing the performance and stability of perovskite solar cells.

[0100] In the above scheme, step 6) specifically includes the following:

[0101] The electron transport layer has a thickness of 20~30nm, and the electron transport layer can use C 60 or PC 61 BM. The buffer layer thickness is 20~30nm, and BCP is used for the buffer layer. The metal electrode thickness is 100nm, and Ag is used for the metal electrode.

[0102] In one embodiment, the bottom interface passivation layer and the top interface passivation layer include a passivating agent; the passivating agent includes at least one selected from PEAI, phosphocholine, and ammonium thiocyanate. Specifically, in the above process, step 5) specifically includes the following:

[0103] At least one of PEAI, phosphocholine, and ammonium thiocyanate was selected as a passivating agent to form a bottom interface passivation layer and a top interface passivation layer by spin coating. The spin coating speed was 4000 rpm, the spin coating time was 30 s, and a dynamic spin coating method was used. After spin coating, the layers were annealed at 100℃ for 10 min to form the passivation layer.

[0104] The following detailed description of the preparation method of the perovskite thin film and the preparation method of the perovskite battery provided by the invention will be provided through specific embodiments.

[0105] Example 1

[0106] This embodiment uses the following method to prepare solar cells:

[0107] 1) Sonicate the ITO sequentially in ITO cleaning agent, deionized water, and isopropanol for 1 hour each. Dry the ITO and treat it with ultraviolet ozone for 25 minutes.

[0108] 2) A hole transport layer (HTL) was prepared on the ITO in step 1), using NiOx and Me-4PACz as the hole transport layers. First, NiOx was immediately spin-coated onto the ITO surface after UV ozone treatment at a speed of 6000 rpm for 30 seconds. After spin-coating, it was placed on a 100°C hot plate for annealing for 10 minutes. Second, after annealing, the ITO was immediately transferred to a glove box for Me-4PACz preparation, with a spin-coating speed of 4000 rpm for 30 seconds. After spin-coating, it was placed on a 100°C hot plate for annealing for 10 minutes.

[0109] 3) Prepare a passivation layer at the buried interface on the substrate in step 2) by spin coating. Dissolve 1 mg / ml of PEAI in isopropanol and use after complete dissolution. Spin coat at 6000 rpm for 30 seconds.

[0110] 4) Prepare a PbI2 thin film (inorganic salt film) in step 3) using spin coating. Dissolve 691.5 mg / ml of PbI2 in a solution of DMF and DMSO at a volume ratio of 9:1. After complete dissolution, prepare the film using spin coating parameters of 1500 rpm for 30 seconds. Immediately after spin coating, perform hot annealing at 70℃ for 1 min.

[0111] 5) Prepare a layer of phosphoric acid choline (phosphoric acid derivative layer) on the PbI2 film in step 4), the structure of which is as follows: Figure 1 As shown, the preparation was carried out by spin coating, with a spin coating speed of 4000 rpm and a spin coating time of 30 s. The spin coating method was dynamic spin coating.

[0112] 6) Coat the phosphate derivative layer from step 5) with an organic salt solution. The organic salt solution has the composition of FAI:MACl in a concentration ratio of 90:10 (mg / ml), dissolved in isopropanol solution. Then, spin-coat the prepared organic salt solution to obtain an organic salt layer. Immediately after spin-coating, anneal at 150°C for 20 minutes in air to form a FAPbI3 perovskite film.

[0113] 7) In step 6), an interface passivation layer is formed on the surface by spin coating. 3 mg / ml of PEAI is dissolved in isopropanol. The spin coating speed is 4000 rpm and the spin coating time is 30 s. After spin coating, the surface is annealed on a hot plate at 100℃ for 10 min.

[0114] 8) In step 7), spin-coating or vapor-depositing an electron transport layer and a buffer layer are performed, followed by vapor-depositing of the metal electrode. The electron transport layer is C. 60 The thickness is 25 nm. The buffer layer is BCP, with a thickness of 22 nm. The metal electrode is Ag, with a thickness of 100 nm.

[0115] The battery structure obtained in Example 1 is shown below. Figure 8 The perovskite film comprises a 30a-inorganic salt film layer, a 30b-phosphate derivative layer, and a 30c-organic salt layer.

[0116] Example 2

[0117] This embodiment uses the following method to prepare solar cells:

[0118] 1) Sonicate the ITO sequentially in ITO cleaning agent, deionized water, and isopropanol for 1 hour each. Dry the ITO and treat it with ultraviolet ozone for 25 minutes.

[0119] 2) A hole transport layer (HTL) was prepared on the ITO in step 1), using NiOx and Me-4PACz as the hole transport layers. First, NiOx was immediately spin-coated onto the ITO surface after UV ozone treatment at a speed of 6000 rpm for 30 seconds. After spin-coating, it was placed on a 100°C hot plate for annealing for 10 minutes. Second, after annealing, the ITO was immediately transferred to a glove box for Me-4PACz preparation, with a spin-coating speed of 4000 rpm for 30 seconds. After spin-coating, it was placed on a 100°C hot plate for annealing for 10 minutes.

[0120] 3) Prepare a passivation layer at the buried interface on the substrate in step 2) by spin coating. Dissolve 1 mg / ml of PEAI in isopropanol and use after complete dissolution. Spin coat at 6000 rpm for 30 seconds.

[0121] 4) Prepare a PbI2 thin film (inorganic salt film) in step 3) using spin coating. Dissolve 691.5 mg / ml of PbI2 in a solution of DMF and DMSO at a volume ratio of 9:1. After complete dissolution, prepare the film using spin coating parameters of 1500 rpm for 30 seconds. Immediately after spin coating, perform hot annealing at 70℃ for 1 min.

[0122] 5) Prepare a 2PACz (phosphate derivative layer) on the PbI2 film in step 4), the structure of which is as follows: Figure 2 As shown, the preparation was carried out by spin coating, with a spin coating speed of 4000 rpm and a spin coating time of 30 s. The spin coating method was dynamic spin coating.

[0123] 6) Coat the 2PACz layer from step 5) with an organic salt solution. The specific composition of the organic salt solution is FAI:MACl, with a concentration ratio of 90:10 (mg / ml), dissolved in isopropanol solution. Then, spin-coat the prepared ammonium salt mixture to obtain the organic salt layer. Immediately after spin-coating, anneal at 150°C for 20 minutes in air to form a FAPbI3 perovskite film.

[0124] 7) In step 6), spin-coat the interface passivation layer on the surface. Dissolve 3 mg / ml PEAI in isopropanol, spin-coat at 4000 rpm for 30 seconds, and anneal on a hot plate at 100°C for 10 minutes after spin-coating.

[0125] 8) In step 7), spin-coating or vapor-depositing an electron transport layer and a buffer layer are performed, followed by vapor-depositing of the metal electrode. The electron transport layer is C. 60 The thickness is 25 nm. The buffer layer is BCP, with a thickness of 22 nm. The metal electrode is Ag, with a thickness of 100 nm.

[0126] The battery structure obtained in Example 2 is the same as that in Example 1.

[0127] Example 3

[0128] This embodiment uses the following method to prepare solar cells:

[0129] 1) Sonicate the ITO sequentially in ITO cleaning agent, deionized water, and isopropanol for 1 hour each. Dry the ITO and treat it with ultraviolet ozone for 25 minutes.

[0130] 2) A hole transport layer (HTL) was prepared on the ITO in step 1), using NiOx and Me-4PACz as the hole transport layers. First, NiOx was immediately spin-coated onto the ITO surface after UV ozone treatment at a speed of 6000 rpm for 30 seconds. After spin-coating, it was placed on a 100°C hot plate for annealing for 10 minutes. Second, after annealing, the ITO was immediately transferred to a glove box for Me-4PACz preparation, with a spin-coating speed of 4000 rpm for 30 seconds. After spin-coating, it was placed on a 100°C hot plate for annealing for 10 minutes.

[0131] 3) Prepare a passivation layer at the buried interface on the substrate in step 2) by spin coating. Dissolve 1 mg / ml of PEAI in isopropanol and use after complete dissolution. Spin coat at 6000 rpm for 30 seconds.

[0132] 4) Prepare a PbI2 thin film (inorganic salt film) in step 3) using spin coating. Dissolve 691.5 mg / ml of PbI2 in a solution of DMF and DMSO at a volume ratio of 9:1. After complete dissolution, prepare the film using spin coating parameters of 1500 rpm for 30 seconds. Immediately after spin coating, perform hot annealing at 70℃ for 1 min.

[0133] 5) Prepare a MeO-2PACz (phosphate derivative layer) layer on the PbI2 film in step 4), the structure of which is as follows: Figure 3 As shown, the preparation was carried out by spin coating, with a spin coating speed of 4000 rpm and a spin coating time of 30 s. The spin coating method was dynamic spin coating.

[0134] 6) Coat the MeO-2PACz layer from step 5) with an organic salt solution. The specific composition of the organic salt solution is FAI:MACl, with a concentration ratio of 90:10 (mg / ml), dissolved in isopropanol solution. Then, spin-coat the prepared ammonium salt mixture to obtain the organic salt layer. Immediately after spin-coating, anneal in air at 150°C for 20 min to form a FAPbI3 perovskite film.

[0135] 7) In step 6), spin-coat the interface passivation layer on the surface. Dissolve 3 mg / ml PEAI in isopropanol, spin-coat at 4000 rpm for 30 seconds, and anneal on a hot plate at 100°C for 10 minutes after spin-coating.

[0136] 8) In step 7), spin-coating or vapor-depositing an electron transport layer and a buffer layer are performed, followed by vapor-depositing of the metal electrode. The electron transport layer is C. 60 The thickness is 25 nm. The buffer layer is BCP, with a thickness of 22 nm. The metal electrode is Ag, with a thickness of 100 nm.

[0137] The battery structure obtained in Example 3 is the same as that in Example 1.

[0138] Comparative Example 1

[0139] This comparative example uses the following method to prepare solar cells:

[0140] 1) Sonicate the ITO sequentially in ITO cleaning agent, deionized water, and isopropanol for 1 hour each. Dry the ITO and treat it with ultraviolet ozone for 25 minutes.

[0141] 2) A hole transport layer (HTL) was prepared on the ITO in step 1), using NiOx and Me-4PACz as the hole transport layers. First, NiOx was immediately spin-coated onto the ITO surface after UV ozone treatment at a speed of 6000 rpm for 30 seconds. After spin-coating, it was placed on a 100°C hot plate for annealing for 10 minutes. Second, after annealing, the ITO was immediately transferred to a glove box for Me-4PACz preparation, with a spin-coating speed of 4000 rpm for 30 seconds. After spin-coating, it was placed on a 100°C hot plate for annealing for 10 minutes.

[0142] 3) Prepare a passivation layer at the buried interface on the substrate in step 2) by spin coating. Dissolve 1.5 mg / ml of phosphocholine in isopropanol and use after complete dissolution. Spin coat at 6000 rpm for 30 s.

[0143] 4) Prepare a PbI2 thin film (inorganic salt film) in step 3) using spin coating. Dissolve 691.5 mg / ml of PbI2 in a solution of DMF and DMSO at a volume ratio of 9:1. After complete dissolution, prepare the film using spin coating parameters of 1500 rpm for 30 seconds. Immediately after spin coating, perform hot annealing at 70℃ for 1 min.

[0144] 5) Coat the substrate with an organic salt solution, specifically FAI:MACl, in a concentration ratio of 90:10 (mg / ml), dissolved in isopropanol solution. Then, spin-coat the prepared ammonium salt mixture to obtain the organic salt layer. Immediately after spin-coating, anneal at 150°C for 20 minutes in air to form a FAPbI3 perovskite film.

[0145] 6) In step 5), spin-coat the interface passivation layer on the surface. Dissolve 3 mg / ml PEAI in isopropanol, spin-coat at 4000 rpm for 30 s, and anneal on a hot plate at 100℃ for 10 min after spin-coating.

[0146] 7) An electron transport layer and a buffer layer are spin-coated or vapor-deposited on top of step 6), and finally, a metal electrode is vapor-deposited. The electron transport layer is C. 60 The thickness is 25 nm. The buffer layer is BCP, with a thickness of 22 nm. The metal electrode is Ag, with a thickness of 100 nm.

[0147] The battery structure diagram obtained in Comparative Example 1 is shown below. Figure 9 The perovskite film includes a 30a-inorganic salt film layer and a 30c-organic salt layer.

[0148] Comparative Example 2

[0149] This comparative example uses the following method to prepare solar cells:

[0150] 1) Sonicate the ITO sequentially in ITO cleaning agent, deionized water, and isopropanol for 1 hour each. Dry the ITO and treat it with ultraviolet ozone for 25 minutes.

[0151] 2) A hole transport layer (HTL) was prepared on the ITO in step 1), using NiOx and Me-4PACz as the hole transport layers. First, NiOx was immediately spin-coated onto the ITO surface after UV ozone treatment at a speed of 6000 rpm for 30 seconds. After spin-coating, it was placed on a 100°C hot plate for annealing for 10 minutes. Second, after annealing, the ITO was immediately transferred to a glove box for Me-4PACz preparation, with a spin-coating speed of 4000 rpm for 30 seconds. After spin-coating, it was placed on a 100°C hot plate for annealing for 10 minutes.

[0152] 3) Prepare a passivation layer at the buried interface on the substrate in step 2) by spin coating. Dissolve 1 mg / ml of PEAI in isopropanol and use after complete dissolution. Spin coat at 6000 rpm for 30 seconds.

[0153] 4) Prepare a PbI2 thin film (inorganic salt film) in step 3) using spin coating. Dissolve 691.5 mg / ml of PbI2 in a solution of DMF and DMSO at a volume ratio of 9:1. After complete dissolution, prepare the film using spin coating parameters of 1500 rpm for 30 seconds. Immediately after spin coating, perform hot annealing at 70℃ for 1 min.

[0154] 5) Based on step 4), an organic salt solution is coated. The specific composition of the organic salt solution is FAI:MACl, with a concentration ratio of 90:10 (mg / ml), dissolved in isopropanol solution. Subsequently, the prepared ammonium salt mixture is spin-coated to obtain an organic salt layer. Immediately after spin-coating, it is annealed in air at 150°C for 20 min to form a FAPbI3 perovskite film.

[0155] 6) In step 5), spin-coat the interface passivation layer on the surface. Dissolve 3 mg / ml of phosphoric acid choline in isopropanol, spin-coat at 4000 rpm for 30 s, and anneal on a hot plate at 100°C for 10 min after spin-coating.

[0156] 7) An electron transport layer and a buffer layer are spin-coated or vapor-deposited on top of step 6), and finally, a metal electrode is vapor-deposited. The electron transport layer is C. 60 The thickness is 25 nm. The buffer layer is BCP, with a thickness of 22 nm. The metal electrode is Ag, with a thickness of 100 nm.

[0157] The battery structure diagram obtained in Comparative Example 2 is the same as that in Comparative Example 1.

[0158] Comparative Example 3

[0159] This comparative example uses the following method to prepare solar cells:

[0160] 1) Sonicate the ITO sequentially in ITO cleaning agent, deionized water, and isopropanol for 1 hour each. Dry the ITO and treat it with ultraviolet ozone for 25 minutes.

[0161] 2) A hole transport layer (HTL) was prepared on the ITO in step 1), using NiOx and Me-4PACz as the hole transport layers. First, NiOx was immediately spin-coated onto the ITO surface after UV ozone treatment at a speed of 6000 rpm for 30 seconds. After spin-coating, it was placed on a 100°C hot plate for annealing for 10 minutes. Second, after annealing, the ITO was immediately transferred to a glove box for Me-4PACz preparation, with a spin-coating speed of 4000 rpm for 30 seconds. After spin-coating, it was placed on a 100°C hot plate for annealing for 10 minutes.

[0162] 3) Prepare a passivation layer at the buried interface on the substrate in step 2) by spin coating. Dissolve 1 mg / ml of PEAI in isopropanol and use after complete dissolution. Spin coat at 6000 rpm for 30 seconds.

[0163] 4) Prepare a PbI2 thin film (inorganic salt film) in step 3) using spin coating. Dissolve 691.5 mg / ml of PbI2 in a solution of DMF and DMSO at a volume ratio of 9:1, add 2 mg / ml of phosphocholine, and after complete dissolution, proceed with film preparation. Spin coating parameters are 1500 rpm for 30 seconds. Immediately after spin coating, perform hot annealing at 70℃ for 1 min.

[0164] 5) Coat the substrate with an organic salt solution, specifically FAI:MACl, in a concentration ratio of 90:10 (mg / ml), dissolved in isopropanol solution. Then, spin-coat the prepared ammonium salt mixture to obtain the organic salt layer. Immediately after spin-coating, anneal at 150°C for 20 minutes in air to form a FAPbI3 perovskite film.

[0165] 6) In step 5), spin-coat the interface passivation layer on the surface. Dissolve 3 mg / ml PEAI in isopropanol, spin-coat at 4000 rpm for 30 s, and anneal on a hot plate at 100℃ for 10 min after spin-coating.

[0166] 7) An electron transport layer and a buffer layer are spin-coated or vapor-deposited on top of step 6), and finally, a metal electrode is vapor-deposited. The electron transport layer is C. 60 The thickness is 25 nm. The buffer layer is BCP, with a thickness of 22 nm. The metal electrode is Ag, with a thickness of 100 nm.

[0167] The battery structure diagram obtained in Comparative Example 3 is the same as that in Comparative Example 1.

[0168] Comparative Example 4

[0169] This comparative example is basically the same as Example 1, except that step 5 is not performed.

[0170] The battery structure diagram obtained in Comparative Example 4 is the same as that in Comparative Example 1.

[0171] Comparative Example 5

[0172] This comparative example is basically the same as Example 1, except that in step 5), phosphocholine is replaced with choline chloride.

[0173] The battery structure diagram obtained in Comparative Example 5 is the same as that in Example 1.

[0174] Test case

[0175] 1. The electrical performance of the solar cells prepared in each embodiment and comparative example was tested, and the JV diagram was obtained. See details. Figure 4 See Table 1.

[0176] Table 1

[0177]

[0178] From Table 1 and Figure 4 It can be seen that, compared with the comparative examples, the solar cells prepared in each embodiment have higher efficiency and fill factor. This may be because the phosphate group can act as a Lewis base to form coordination bonds with uncoordinated lead ions in the perovskite, thereby reducing the formation of defects, improving the film quality, and enhancing the performance and stability of the perovskite solar cell.

[0179] Furthermore, the solar cell prepared in Example 1 exhibits better electrical performance than the solar cells prepared in Comparative Examples 1-3. This may be because phosphocholine has limited passivation effects at the buried interface and on the perovskite surface, only passivating shallow surface defects. Adding it to the PbI2 precursor solution affects charge transport, while introducing a buffer layer on the PbI2 surface that can act as a perovskite crystallization layer helps to obtain a dense perovskite film.

[0180] SEM observations were performed on the solar cells prepared in Example 1, Comparative Example 1, and Comparative Example 2, respectively, and the results were obtained. Figure 5 , Figure 6 , Figure 7 .contrast Figures 5 to 7 It can be seen that after the same placement time, Figure 5 The denser battery is attributed to the effective passivation of defects and improved film quality. Figure 6 , Figure 7 The battery contains more PbI2, which is more easily degraded, thus clearly corresponding to the improved on-state voltage performance.

[0181] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for preparing a perovskite thin film, characterized in that, Includes the following steps: An inorganic salt thin film layer is formed to obtain the first intermediate; A phosphate derivative layer is formed on the inorganic salt film of the first intermediate to obtain the second intermediate; An organic salt solution is coated on the surface of the phosphate derivative layer of the second intermediate, and a first annealing treatment is performed to obtain the perovskite film. The phosphate derivative layer includes at least one of 2PACz, MeO-2PACz, and phosphocholine.

2. The method according to claim 1, characterized in that, The inorganic salt thin film layer includes PbI2.

3. The method according to claim 2, characterized in that, The organic salt solution includes FAI and MACl.

4. The method according to claim 3, characterized in that, In the organic salt solution, the concentration of FAI is 60~100 mg / mL; and / or the concentration of MACl is 5~20 mg / mL.

5. The method according to claim 3 or 4, characterized in that, Forming a phosphoric acid derivative layer on the inorganic salt film of the first intermediate specifically includes coating the surface of the inorganic salt film with a phosphorus source solution; The phosphorus source solution includes the phosphoric acid derivative; The method of coating the phosphorus source solution is selected from at least one of slot coating, doctor blade coating, spraying, spin coating and screen printing.

6. The method according to claim 5, characterized in that, The phosphorus source solution includes a phosphoric acid derivative and a solvent, wherein the solvent includes isopropanol, and the concentration of the phosphoric acid derivative is 1-3 mg / mL.

7. A perovskite thin film, characterized in that, It includes an inorganic salt film layer, a phosphate derivative layer, and an organic salt layer stacked sequentially.

8. The perovskite thin film according to claim 7, characterized in that, The phosphate derivative layer includes at least one of 2PACz, MeO-2PACz, and phosphocholine; The inorganic salt thin film layer includes PbI2.

9. A solar cell, characterized in that, Includes the perovskite thin film as described in claim 7 or 8.

10. A method for preparing a solar cell, characterized in that, Includes the following steps: A hole transport layer, a buried interface passivation layer, a perovskite thin film, a top interface passivation layer, an electron transport layer, a buffer layer, and a metal electrode are sequentially formed on one side surface of a transparent conductive substrate to obtain the solar cell. The perovskite film comprises an inorganic salt film layer, a phosphate derivative layer, and an organic salt layer stacked sequentially; the buried interface passivation layer and the top interface passivation layer comprise passivating agents; The passivating agent is selected from at least one of PEAI, phosphocholine, and ammonium thiocyanate.

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