Preparation method of perovskite cell, perovskite cell and laminated cell

Abstract

The invention provides a preparation method of a perovskite cell, the perovskite cell and a laminated cell. The method comprises the following steps: providing a substrate, and forming a hole transport layer on one side of the substrate; a first material layer and a second material layer are sequentially formed on the side, away from the substrate, of the hole transport layer, a framework layer is obtained, the first material layer comprises iodide, and the second material layer comprises bromide; forming a cation layer on one side, far away from the hole transport layer, of the skeleton layer, and performing annealing treatment to obtain a perovskite light absorption layer; forming an electron transport layer on one side, far away from the hole transport layer, of the perovskite light absorption layer; and forming an electrode layer on one side, far away from the perovskite light absorption layer, of the electron transport layer. The method can improve the photoelectric conversion efficiency of the perovskite cell.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of perovskite cells, in particular, to a preparation method of perovskite cell, perovskite cell and laminated cell. BACKGROUND

[0002] Solar photovoltaic technology is a technology for directly converting light energy into electrical energy, wherein, perovskite solar cells have excellent photoelectric properties, simple device structure and low cost.

[0003] However, the existing perovskite solar cell has a problem of halogen phase separation in the perovskite light-absorbing layer, which increases the non-radiative recombination loss of carriers, resulting in device performance degradation and affecting the photoelectric conversion efficiency. Therefore, there is an urgent need for a perovskite cell to solve the above problems.

[0004] The above information disclosed in the background section is only used to enhance the understanding of the background of the technology described herein, therefore, the background section can include certain information which is not known to those skilled in the art as prior art in the country. SUMMARY

[0005] The main purpose of the present application is to provide a preparation method of perovskite cell, perovskite cell and laminated cell, to solve the problem of how to improve the photoelectric conversion efficiency of perovskite cell in the prior art.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a preparation method of perovskite cell is provided, comprising: providing a substrate, and forming a hole transport layer on one side of the substrate; forming a first material layer and a second material layer on the side of the hole transport layer away from the substrate in sequence, to obtain a skeleton layer, wherein the first material layer comprises iodide, and the second material layer comprises bromide; forming a cation layer on the side of the skeleton layer away from the hole transport layer and performing annealing treatment, to obtain a perovskite light-absorbing layer; forming an electron transport layer on the side of the perovskite light-absorbing layer away from the hole transport layer; forming an electrode layer on the side of the electron transport layer away from the perovskite light-absorbing layer.

[0007] In some embodiments, forming a first material layer and a second material layer on the side of the hole transport layer away from the substrate in sequence to obtain a skeleton layer comprises: forming a first material layer with a first thickness on the side of the hole transport layer away from the substrate, the material of the first material layer comprising lead iodide and cesium iodide, and the first thickness being 200-250 nm; forming a second material layer with a second thickness on the side of the first material layer away from the hole transport layer, the material of the second material layer comprising lead iodide and cesium bromide, and the second thickness being 200-250 nm.

[0008] In some embodiments, forming a first material layer of a first thickness on a side of the hole transport layer away from the substrate comprises: co-evaporating a first evaporation source and a second evaporation source on the side of the hole transport layer away from the substrate to obtain the first material layer of the first thickness, wherein the first evaporation source comprises the lead iodide and the second evaporation source comprises the cesium iodide, and a ratio of an evaporation rate of the first evaporation source to an evaporation rate of the second evaporation source is (6-10):1.

[0009] In some embodiments, forming a second material layer of a second thickness on a side of the first material layer away from the hole transport layer comprises: co-evaporating a third evaporation source and a fourth evaporation source on the side of the first material layer away from the hole transport layer to obtain the second material layer of the second thickness, wherein the third evaporation source comprises the lead iodide and the fourth evaporation source comprises the cesium bromide, and a ratio of an evaporation rate of the third evaporation source to an evaporation rate of the fourth evaporation source is (6-10):1.

[0010] In some embodiments, forming a cation layer on a side of the skeleton layer away from the hole transport layer and performing annealing treatment to obtain a perovskite light-absorbing layer comprises: forming a cation layer on the side of the skeleton layer away from the hole transport layer, the cation layer comprising an organic halide ammonium salt; and performing annealing treatment on the cation layer, wherein an annealing temperature is 120-150°C and an annealing time is 10-15 min.

[0011] In some embodiments, forming a cation layer on a side of the skeleton layer away from the hole transport layer comprises: coating an isopropyl alcohol solution of the organic halide ammonium salt on the side of the skeleton layer away from the hole transport layer to obtain the cation layer, wherein the organic halide ammonium salt comprises formamidinium iodide, methylamine iodide, and methylamine chloride, a molar concentration of the formamidinium iodide is greater than a molar concentration of the methylamine iodide, the molar concentration of the methylamine iodide is greater than a molar concentration of the methylamine chloride, a coating rate is 12-15 mm / s, a coating humidity is 40-50%, and a coating temperature is 20-25°C.

[0012] In some embodiments, after forming a cation layer on a side of the skeleton layer away from the hole transport layer and performing annealing treatment to obtain a perovskite light-absorbing layer, before forming an electron transport layer on a side of the perovskite light-absorbing layer away from the hole transport layer, the method further comprises: forming a passivation layer on the side of the perovskite light-absorbing layer away from the hole transport layer, a material of the passivation layer comprising octylammonium iodide.

[0013] In some embodiments, after the electron transport layer is formed on the side of the perovskite light-absorbing layer away from the hole transport layer, before the electrode layer is formed on the side of the electron transport layer away from the perovskite light-absorbing layer, the method further comprises: forming a third thickness of a buffer layer on the side of the electron transport layer away from the perovskite light-absorbing layer, wherein the third thickness is 20-30 nm, and the material of the buffer layer comprises tin dioxide; and forming a fourth thickness of a transparent conductive layer on the side of the buffer layer away from the electron transport layer, wherein the fourth thickness is 45-50 nm, and the material of the transparent conductive layer comprises indium tin oxide or indium zinc oxide.

[0014] To achieve the above object, according to another aspect of the present application, there is provided a perovskite cell prepared by any one of the preparation methods of the perovskite cell.

[0015] To achieve the above object, according to still another aspect of the present application, there is provided a laminated cell comprising: a crystalline silicon bottom cell; an intermediate layer on one side of the crystalline silicon bottom cell; and a perovskite cell on the side of the intermediate layer away from the crystalline silicon bottom cell, the perovskite cell being prepared by any one of the preparation methods of the perovskite cell.

[0016] The technical solution of the present application provides a preparation method of a perovskite cell. First, a substrate is provided, and a hole transport layer is formed on one side of the substrate. Then, a first material layer and a second material layer are sequentially formed on the side of the hole transport layer away from the substrate to obtain a skeleton layer, wherein the first material layer comprises iodide, and the second material layer comprises bromide. Then, a cation layer is formed on the side of the skeleton layer away from the hole transport layer, and annealing treatment is performed to obtain a perovskite light-absorbing layer. Finally, an electron transport layer is formed on the side of the perovskite light-absorbing layer away from the hole transport layer, and an electrode layer is formed on the side of the electron transport layer away from the perovskite light-absorbing layer. By forming the first material layer and the second material layer on the side of the hole transport layer away from the substrate to obtain the skeleton layer, the first material layer comprises iodide, and the second material layer comprises bromide. Since the band gap of iodide is different from the band gap of bromide, in the subsequent annealing process of the cation layer, the skeleton layer has a band gap and an energy level structure that change sequentially in the direction of the thickness of the substrate. This can improve the long-wave band edge absorption of the finally formed perovskite light-absorbing layer, enhance the built-in electric field, promote the separation and extraction of carriers, reduce non-radiative recombination loss, improve the voltage and fill factor of the perovskite cell, and thus improve the photoelectric conversion efficiency of the perovskite cell, thereby solving the technical problem of how to improve the photoelectric conversion efficiency of the perovskite cell in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1 A schematic flowchart of a method for preparing a perovskite solar cell according to an embodiment of this application is shown.

[0019] Figure 2 (a) shows a schematic diagram of the energy levels of the hole transport layer, perovskite light-absorbing layer, and electron transport layer in the prior art. Figure 2 (b) shows a schematic diagram of the energy levels of the hole transport layer, perovskite light-absorbing layer and electron transport layer of this application;

[0020] Figure 3 A schematic diagram of the structure of a perovskite solar cell according to an embodiment of this application is shown;

[0021] Figure 4 A schematic diagram of a stacked battery structure according to an embodiment of this application is shown;

[0022] Figure 5 A schematic diagram showing the photoluminescence spectral test results of perovskite solar cells according to embodiments and comparative examples of this application is illustrated.

[0023] Figure 6 A schematic diagram showing the long-term stability test results of stacked batteries according to embodiments and comparative examples of this application is illustrated.

[0024] The above figures include the following reference numerals:

[0025] 20. Substrate; 21. Hole transport layer; 22. Perovskite light-absorbing layer; 23. Electron transport layer; 24. Electrode layer; 25. Passivation layer; 26. Buffer layer; 27. Transparent conductive layer; 28. Antireflection layer; 30. Crystalline silicon base cell; 40. Intermediate layer; 50. Perovskite cell. Detailed Implementation

[0026] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0028] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0029] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.

[0030] As described in the background section, in order to solve the problem of how to improve the photoelectric conversion efficiency of perovskite solar cells in the prior art, the embodiments of this application provide a method for preparing a perovskite solar cell, a perovskite solar cell, and a tandem solar cell.

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0032] Figure 1 This is a flowchart of a method for fabricating a perovskite solar cell according to an embodiment of this application. Figure 1 As shown, the method includes the following steps:

[0033] Step S101: Provide a substrate and form a hole transport layer on one side of the substrate;

[0034] In some embodiments, the substrate can be a rigid material such as glass, or a flexible material such as polyethylene terephthalate (PET) or polyimide (PI). After providing the substrate, but before forming the hole transport layer, the substrate can be cleaned to further remove impurities and improve reliability. The hole transport layer can be formed on one side of the substrate using physical vapor deposition (PVD), and the material of the hole transport layer can be nickel oxide (NiO). x Inorganic materials such as cuprous thiocyanate (CuSCN) and cuprous iodide (CuI) can also be organic materials such as Spiro-OMeTAD, or polymeric materials such as PTAA and PEDOT:PSS, with a thickness range of 20~50nm.

[0035] Step S102: A first material layer and a second material layer are sequentially formed on the side of the hole transport layer away from the substrate to obtain a framework layer, wherein the first material layer includes an iodide and the second material layer includes a bromide.

[0036] Specifically, a framework layer can be formed on the side of the hole transport layer away from the substrate by vapor deposition. The methods for forming the first material layer and the second material layer can be the same or different. The iodide can be lead iodide or cesium iodide; the bromide can be lead bromide or cesium bromide. The thickness of the framework layer can be 400~500 nm, and the thicknesses of the first material layer and the second material layer can be the same or different.

[0037] Step S103: A cation layer is formed on the side of the skeleton layer away from the hole transport layer and annealed to obtain a perovskite light-absorbing layer.

[0038] Specifically, the aforementioned cation layer can be formed by using a cation salt dissolved in a polar solvent and spin-coating it onto the surface of the framework layer away from the hole transport layer. A schematic diagram of the energy levels of the hole transport layer, perovskite light-absorbing layer, and electron transport layer in the prior art is shown below. Figure 2 As shown in (a), the energy levels of the hole transport layer are -5.3 to -1.7 eV, the energy levels of the perovskite absorber layer are -5.57 to -3.84 eV, and the energy levels of the electron transport layer are -6.2 to -4.0 eV. During the annealing process of the cation layer, the perovskite absorber layer exhibits a changing energy level structure along the substrate thickness direction, resulting in the following... Figure 2(b) shows a schematic diagram of the energy levels of the hole transport layer, the perovskite light-absorbing layer, and the electron transport layer. The energy levels of the hole transport layer remain at -5.3 to -1.7 eV, the energy levels of the electron transport layer remain at -6.2 to -4.0 eV, while the perovskite light-absorbing layer has a changing energy level structure from -5.46 to -3.79 eV to -5.57 to -3.84 eV.

[0039] Step S104: An electron transport layer is formed on the side of the perovskite light-absorbing layer away from the hole transport layer.

[0040] In practical applications, an electron transport layer can be formed on the side of the perovskite light-absorbing layer away from the hole transport layer by vapor deposition. The material of this layer can be C. 60 Or C 70 Its thickness ranges from 15 to 20 nm. The evaporation rate of the electron transport layer can be 0.2 to 0.3 Å / s.

[0041] Step S105: An electrode layer is formed on the side of the electron transport layer away from the perovskite light-absorbing layer.

[0042] In practical applications, the electrode layer can be made of materials such as silver, gold, or aluminum. The electrode layer can be formed on the side of the electron transport layer away from the perovskite light-absorbing layer by vapor deposition, with an evaporation rate of 2–4 Å / s. Its thickness can range from 150 to 300 nm.

[0043] This embodiment provides a method for fabricating a perovskite solar cell. First, a substrate is provided, and a hole transport layer is formed on one side of the substrate. Then, a first material layer and a second material layer are sequentially formed on the side of the hole transport layer away from the substrate to obtain a framework layer. The first material layer includes an iodide, and the second material layer includes a bromide. Next, a cation layer is formed on the side of the framework layer away from the hole transport layer and annealed to obtain a perovskite light-absorbing layer. Finally, an electron transport layer is formed on the side of the perovskite light-absorbing layer away from the hole transport layer. An electrode layer is formed on the side of the electron transport layer away from the perovskite light-absorbing layer. By forming a first material layer and a second material layer on the side of the hole transport layer away from the substrate, a framework layer is obtained. The first material layer includes iodide, and the second material layer includes bromide. Since the band gaps of iodide and bromide are different, during the subsequent cation layer annealing process, the framework layer has a sequentially changing band gap and energy level structure along the substrate thickness direction. This can improve the long-wavelength band edge absorption of the finally formed perovskite light-absorbing layer, enhance the built-in electric field, promote carrier separation and extraction, reduce non-radiative recombination losses, and improve the voltage and fill factor of the perovskite cell, thereby improving its photoelectric conversion efficiency. This solves the technical problem of how to improve the photoelectric conversion efficiency of perovskite cells in the prior art.

[0044] In specific implementation, step S102 can be achieved through the following steps: Step S1021, forming a first material layer of a first thickness on the side of the hole transport layer away from the substrate, the first material layer comprising lead iodide and cesium iodide, the first thickness being 200~250 nm; Step S1022, forming a second material layer of a second thickness on the side of the first material layer away from the hole transport layer, the second material layer comprising lead iodide and cesium bromide, the second thickness being 200~250 nm. Forming the first and second material layers with the aforementioned thickness range and materials can further improve the stability of the framework layer, thereby further improving the photoelectric conversion efficiency of the perovskite solar cell.

[0045] In the above implementation process, the first thickness can be any value among 200nm, 210nm, 220nm, 230nm, 240nm, and 250nm, or between any two of the above values. The second thickness can be any value among 200nm, 210nm, 220nm, 230nm, 240nm, and 250nm, or between any two of the above values. The band gap of the first material layer is approximately 1.67eV, and the band gap of the second material layer is approximately 1.73eV, which can form a gradient band gap during the subsequent annealing process.

[0046] To further improve the reliability of the first material layer, step S1021 of this application can be implemented through the following steps: Step S10211, a first evaporation source and a second evaporation source are co-deposited on the side of the hole transport layer away from the substrate to obtain the first material layer of the first thickness. The first evaporation source includes lead iodide, and the second evaporation source includes cesium iodide. The ratio of the evaporation rate of the first evaporation source to the evaporation rate of the second evaporation source is (6~10):1. This method can regulate the band gap and phase stability of the first material layer by controlling the ratio of the evaporation rate of the first evaporation source to the evaporation rate of the second evaporation source, suppressing ion migration and phase separation, thereby further ensuring that the first material layer has a good morphology, providing conditions for subsequent cation layer penetration and reaction completion.

[0047] In the above implementation scheme, the ratio of the evaporation rate of the first evaporation source to the evaporation rate of the second evaporation source can be 6:1, 7:1, 8:1, 9:1, or 10:1, or it can be between any two of the above ratios.

[0048] Step S1022 can also be implemented in other ways, for example: in step S10221, a third evaporation source and a fourth evaporation source are co-deposited on the side of the first material layer away from the hole transport layer to obtain the second material layer of the second thickness. The third evaporation source includes lead iodide, and the fourth evaporation source includes cesium bromide. The ratio of the evaporation rate of the third evaporation source to the evaporation rate of the fourth evaporation source is (6~10):1. This method can regulate the band gap and phase stability of the second material layer by controlling the ratio of the evaporation rate of the third evaporation source to the evaporation rate of the fourth evaporation source, suppressing ion migration and phase separation, thereby further ensuring that the second material layer has a good morphology, providing conditions for subsequent cation layer penetration and reaction completion.

[0049] In the above implementation scheme, the ratio of the evaporation rate of the third evaporation source to the evaporation rate of the fourth evaporation source can be 6:1, 7:1, 8:1, 9:1, or 10:1, or it can be between any two of the above ratios. The specific steps for forming the first and second material layers using the above dual-source co-evaporation process are as follows: 1. Pre-melting: Briefly heat the two sources to slightly above the working temperature to melt the material surface and release gas; avoid "splattering" during formal evaporation. 2. Simultaneous co-evaporation: Simultaneously turn on the two evaporation sources and continue evaporating at a preset rate ratio; the substrate can be rotated (rotation speed 10~30 rpm) to improve film thickness uniformity; the substrate temperature can be maintained at 50~70°C to promote molecular migration and reduce pinholes; the deposition time can be calculated according to the target thickness, for example: a 400nm framework layer takes approximately 20~40 minutes to deposit. 3. Real-time monitoring of the total deposition rate and the proportion of each component.

[0050] In some embodiments, step S103 can be implemented through the following steps: Step S1031, forming a cation layer on the side of the framework layer away from the hole transport layer, the cation layer comprising an organoammonium halide salt; Step S1032, annealing the cation layer, wherein the annealing temperature is 120~150℃ and the annealing time is 10~15min. This method uses an organoammonium halide salt as the cation layer to further construct a key precursor for perovskite, and the annealing temperature and time being within the aforementioned ranges can further improve the stability and reliability of the obtained perovskite light-absorbing layer.

[0051] In the above implementation scheme, organohalogenated ammonium salts are a class of compounds consisting of an organic cation (a nitrogen-containing organic group, which can be an ammonium ion derivative) and a halide anion (…). C B , Ionic compounds composed of methylammonium iodide, methylammonium bromide, methylammonium chloride, formamidinium iodide, formamidinium bromide, and other small molecule alkyl / alkylamines, phenylethyl compounds, long-chain alkyl compounds, aromatic heterocyclic compounds, and quaternary ammonium salts.

[0052] Step S1031 can be achieved through the following steps: Step S10311, coating the side of the skeleton layer away from the hole transport layer with an isopropanol solution of the organoammonium halide salt to obtain the cation layer. The organoammonium halide salt includes formamidinium iodide, methylamine iodide, and methylamine chloride. The molar concentration of formamidinium iodide is greater than that of methylamine iodide, and the molar concentration of methylamine iodide is greater than that of methylamine chloride. The coating rate is 12-15 mm / s, the coating humidity is 40-50%, and the coating temperature is 20-25°C. This method, using organoammonium halide salts within the above molar concentration range, the coating rate within the above range, the coating humidity, and the coating temperature, can further improve the reliability of the cation layer.

[0053] In practical applications, the molar concentration of formamidinium iodide can be 0.3~0.6M, the molar concentration of methylamine iodide can be 0.1~0.3M, and the molar concentration of methylamine chloride can be 0.05~0.025M. In some embodiments, a slot coating process can be used to coat the isopropanol solution of the organohalogen ammonium salt. The slot coating process parameters are as follows: the distance between the cutter head and the substrate can be 90~100μm, the coating speed is 10~15mm / s, the wet film thickness is 10~11μm; the air knife pressure is 0.1~0.15Mpa; the coating environment can be an air environment with a humidity of 40%~50% and a temperature of 20~25℃.

[0054] Following step S103 and preceding step S104, the process further includes step S106, where a passivation layer is formed on the side of the perovskite light-absorbing layer away from the hole transport layer. The passivation layer is made of octylammonium iodide. This passivation layer can suppress non-radiative recombination, thereby further improving the efficiency of the perovskite solar cell.

[0055] In the above implementation scheme, a passivation layer can be formed on the side of the perovskite light-absorbing layer away from the hole transport layer using a slit coating process. The concentration of octylammonium iodide can be 0.8~1 mg / mL.

[0056] Following step S104 and preceding step S105, the process includes: step S107, forming a buffer layer of third thickness on the side of the electron transport layer away from the perovskite light-absorbing layer, wherein the third thickness is 20-30 nm, and the material of the buffer layer includes tin dioxide; step S108, forming a transparent conductive layer of fourth thickness on the side of the buffer layer away from the electron transport layer, wherein the fourth thickness is 45-50 nm, and the material of the transparent conductive layer includes indium tin oxide or indium zinc oxide. The buffer layer can "bridge" the energy levels of the material layers on both sides, reducing the carrier extraction barrier, and the transparent conductive layer can collect carriers transported from the charge transport layer and guide them to the external circuit, thereby comprehensively improving the photoelectric conversion efficiency of the perovskite solar cell.

[0057] In some embodiments, an atomic layer deposition (ALD) process can be used to form a third buffer layer on the side of the electron transport layer away from the perovskite light-absorbing layer. The transparent conductive layer can be formed using PVD.

[0058] In another typical embodiment of this application, a perovskite solar cell is provided. The perovskite solar cell is prepared using any of the above-described methods for preparing perovskite solar cells, such as... Figure 3 As shown, the perovskite solar cell includes:

[0059] Base 20;

[0060] Hole transport layer 21 is located on the surface of one side of substrate 20;

[0061] The perovskite light-absorbing layer 22 is located on the surface of the hole transport layer 21 on the side away from the substrate 20.

[0062] Electron transport layer 23 is located on the surface of perovskite light-absorbing layer 22 on the side away from hole transport layer 21;

[0063] Electrode layer 24 is located on the surface of electron transport layer 23 on the side away from perovskite light-absorbing layer 22.

[0064] The substrate 20 can be made of rigid materials such as glass, or flexible materials such as polyethylene terephthalate (PET) or polyimide (PI). The hole transport layer 21 can be made of inorganic materials such as nickel oxide (NiOx), cuprous thiocyanate (CuSCN), and cuprous iodide (CuI), or organic materials such as Spiro-OMeTAD, or polymeric materials such as PTAA and PEDOT:PSS. The electron transport layer 23 can be made of C... 60 Or C 70 The electrode layer 24 can be made of materials such as silver, gold, or aluminum.

[0065] like Figure 3 As shown, the above-mentioned perovskite solar cell also includes:

[0066] Passivation layer 25 is located between perovskite light-absorbing layer 22 and electron transport layer 23;

[0067] Buffer layer 26 is located on the surface of electron transport layer 23 on the side away from perovskite light-absorbing layer 22;

[0068] A transparent conductive layer 27 is located on the surface of the buffer layer 26 away from the electron transport layer 23;

[0069] The antireflective layer 28 is located on the surface of the transparent conductive layer 27 away from the buffer layer 26.

[0070] The passivation layer 25 is made of octylammonium iodide, the buffer layer 26 is made of tin dioxide, and the transparent conductive layer 27 is made of indium tin oxide or indium zinc oxide. The antireflection layer 28 can be made of materials such as magnesium fluoride and lithium fluoride.

[0071] In another typical embodiment of this application, a stacked battery is provided, such as... Figure 4 As shown, the tandem battery includes:

[0072] 30 crystalline silicon bottom cell;

[0073] The aforementioned crystalline silicon base cell 30 can be one of the following: a tunnel oxide passivated contact (TOPCon) cell, a heterojunction with intrinsic thin-layer (HJT) cell, or an interdigitated back contact (IBC) cell. Other types of crystalline silicon cells may also be used, but these will not be elaborated upon here.

[0074] The intermediate layer 40 is located on one side of the aforementioned crystalline silicon bottom cell 30;

[0075] In practical applications, the above-mentioned intermediate layer 40 can be fabricated using PVD.

[0076] The perovskite solar cell 50 is located on the side of the intermediate layer 40 away from the crystalline silicon bottom cell 30. The perovskite solar cell 50 is prepared by any of the above-described methods for preparing perovskite solar cells 50.

[0077] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the perovskite solar cell preparation method of this application will be described in detail below with reference to specific embodiments and comparative examples.

[0078] Example

[0079] This embodiment relates to a specific method for preparing a perovskite solar cell, including the following steps:

[0080] Step S1: Provide a substrate and form a hole transport layer with a thickness of 20 nm on one side of the substrate. The material of the hole transport layer is nickel oxide.

[0081] Step S2: A first material layer of 250 nm and a second material layer of 250 nm are sequentially formed on the side of the hole transport layer away from the substrate to obtain a framework layer, wherein the first material layer is lead iodide and cesium iodide, and the second material layer is lead iodide and cesium bromide.

[0082] Step S3: A cation layer is formed on the side of the above-mentioned framework layer away from the above-mentioned hole transport layer and annealed to obtain a perovskite light-absorbing layer, wherein the annealing temperature is 150°C and the annealing time is 15 min.

[0083] Step S4: Form a 15nm electron transport layer on the side of the perovskite light-absorbing layer away from the hole transport layer. The material of the electron transport layer is C. 60 ;

[0084] Step S5: Form a 200nm silver electrode layer on the side of the electron transport layer away from the perovskite light-absorbing layer.

[0085] Comparative Example

[0086] This comparative example relates to a specific method for preparing a perovskite solar cell. The only difference between this comparative example and the embodiment is that in step S2, a single-layer framework layer is formed, and the materials are lead iodide and cesium bromide.

[0087] The perovskite solar cells prepared by the methods described in the examples and comparative examples were subjected to photoluminescence spectroscopy tests, and the results were as follows: Figure 5 The results are shown. Compared with the comparative example, the light intensity of the perovskite solar cell in the embodiment is significantly improved, indicating an improvement in the performance of the perovskite solar cell and a reduction in nonradiative recombination.

[0088] The perovskite solar cells prepared by the methods described in the examples and comparative examples were tested under the following conditions: AM1.5, 1000 W / m 2 The test environment temperature was 25℃, and the effective battery area was 20.38cm². 2 The test results are shown in Table 1, including photoelectric conversion efficiency (PCE) and open-circuit voltage (V). OC ), short-circuit current density (J SC ) and fill factor (FF).

[0089] Table 1

[0090]

[0091] As can be seen from the data results in Table 1, compared with the comparative example, the V of the stacked battery in the embodiment is... OC And FF significantly improved.

[0092] Furthermore, long-term stability tests were conducted on the aforementioned stacked battery, and the results were as follows: Figure 6 The results are shown. The storage conditions were atmospheric conditions with a relative humidity of approximately 50%, and the test duration was 1200 hours. Compared with the comparative example, after 1200 hours, the performance of the tandem battery in the embodiment still remained above 90% of the initial efficiency, indicating that the solution of the embodiment can improve the performance and long-term stability of the tandem battery device.

[0093] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0094] The method for fabricating a perovskite solar cell according to this application firstly involves providing a substrate and forming a hole transport layer on one side of the substrate; then, a first material layer and a second material layer are sequentially formed on the side of the hole transport layer away from the substrate to obtain a framework layer, wherein the first material layer includes an iodide and the second material layer includes a bromide; next, a cation layer is formed on the side of the framework layer away from the hole transport layer and annealed to obtain a perovskite light-absorbing layer; finally, an electron transport layer is formed on the side of the perovskite light-absorbing layer away from the hole transport layer; and an electrode layer is formed on the side of the electron transport layer away from the perovskite light-absorbing layer. By forming a first material layer and a second material layer on the side of the hole transport layer away from the substrate, a framework layer is obtained. The first material layer includes iodide, and the second material layer includes bromide. Since the band gaps of iodide and bromide are different, during the subsequent cation layer annealing process, the framework layer has a sequentially changing band gap and energy level structure along the substrate thickness direction. This can improve the long-wavelength band edge absorption of the finally formed perovskite light-absorbing layer, enhance the built-in electric field, promote carrier separation and extraction, reduce non-radiative recombination losses, and improve the voltage and fill factor of the perovskite cell, thereby improving its photoelectric conversion efficiency. This solves the technical problem of how to improve the photoelectric conversion efficiency of perovskite cells in the prior art.

[0095] 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.

[0096] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a perovskite solar cell, characterized in that, include: A substrate is provided, and a hole transport layer is formed on one side of the substrate; A first material layer and a second material layer are sequentially formed on the side of the hole transport layer away from the substrate to obtain a framework layer, wherein the first material layer includes an iodide and the second material layer includes a bromide; A cation layer is formed on the side of the framework layer away from the hole transport layer and then annealed to obtain a perovskite light-absorbing layer. An electron transport layer is formed on the side of the perovskite light-absorbing layer away from the hole transport layer; An electrode layer is formed on the side of the electron transport layer away from the perovskite light-absorbing layer.

2. The method for preparing a perovskite solar cell according to claim 1, characterized in that, A first material layer and a second material layer are sequentially formed on the side of the hole transport layer away from the substrate to obtain a framework layer, comprising: A first material layer of a first thickness is formed on the side of the hole transport layer away from the substrate. The material of the first material layer includes lead iodide and cesium iodide, and the first thickness is 200~250 nm. A second material layer of a second thickness is formed on the side of the first material layer away from the hole transport layer. The material of the second material layer includes lead iodide and cesium bromide, and the second thickness is 200~250 nm.

3. The method for preparing a perovskite solar cell according to claim 2, characterized in that, A first material layer of a first thickness is formed on the side of the hole transport layer away from the substrate, comprising: A first evaporation source and a second evaporation source are co-deposited on the side of the hole transport layer away from the substrate to obtain the first material layer of the first thickness, wherein the first evaporation source includes the lead iodide, the second evaporation source includes the cesium iodide, and the ratio of the evaporation rate of the first evaporation source to the evaporation rate of the second evaporation source is (6~10):

1.

4. The method for preparing a perovskite solar cell according to claim 2, characterized in that, A second material layer of a second thickness is formed on the side of the first material layer away from the hole transport layer, comprising: A third evaporation source and a fourth evaporation source are co-deposited on the side of the first material layer away from the hole transport layer to obtain a second material layer of the second thickness, wherein the third evaporation source includes lead iodide, the fourth evaporation source includes cesium bromide, and the ratio of the evaporation rate of the third evaporation source to the evaporation rate of the fourth evaporation source is (6~10):

1.

5. The method for preparing a perovskite solar cell according to claim 1, characterized in that, A cation layer is formed on the side of the framework layer away from the hole transport layer and then annealed to obtain a perovskite light-absorbing layer, comprising: A cation layer is formed on the side of the framework layer away from the hole transport layer, and the cation layer comprises an organoammonium halide salt; The cationic layer is annealed at a temperature of 120-150°C for 10-15 minutes.

6. The method for preparing a perovskite solar cell according to claim 5, characterized in that, A cation layer is formed on the side of the framework layer away from the hole transport layer, comprising: An isopropanol solution of the organohalogen ammonium salt is coated on the side of the skeleton layer away from the hole transport layer to obtain the cation layer. The organohalogen ammonium salt includes formamidinium iodide, methylamine iodide, and methylamine chloride. The molar concentration of formamidinium iodide is greater than that of methylamine iodide, and the molar concentration of methylamine iodide is greater than that of methylamine chloride. The coating rate is 12-15 mm / s, the coating humidity is 40-50%, and the coating temperature is 20-25°C.

7. The method for preparing a perovskite solar cell according to any one of claims 1 to 6, characterized in that, After forming a cation layer on the side of the framework layer away from the hole transport layer and annealing it to obtain a perovskite light-absorbing layer, and before forming an electron transport layer on the side of the perovskite light-absorbing layer away from the hole transport layer, the method further includes: A passivation layer is formed on the side of the perovskite light-absorbing layer away from the hole transport layer, and the material of the passivation layer includes octylammonium iodide.

8. The method for preparing a perovskite solar cell according to any one of claims 1 to 6, characterized in that, After forming an electron transport layer on the side of the perovskite light-absorbing layer away from the hole transport layer, and before forming an electrode layer on the side of the electron transport layer away from the perovskite light-absorbing layer, the method further includes: A buffer layer of a third thickness is formed on the side of the electron transport layer away from the perovskite light-absorbing layer, wherein the third thickness is 20~30nm, and the material of the buffer layer includes tin dioxide; A fourth transparent conductive layer with a thickness of 45-50 nm is formed on the side of the buffer layer away from the electron transport layer. The material of the transparent conductive layer includes indium tin oxide or indium zinc oxide.

9. A perovskite battery, characterized in that, The perovskite solar cell is prepared using any one of the perovskite solar cell preparation methods described in claims 1 to 8.

10. A stacked battery, characterized in that, include: Crystalline silicon bottom cells; The intermediate layer is located on one side of the crystalline silicon bottom cell; A perovskite solar cell is located on the side of the intermediate layer away from the crystalline silicon base cell, and the perovskite solar cell is prepared by any one of the perovskite solar cell preparation methods according to claims 1 to 8.

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