Perovskite cell, preparation method thereof and perovskite laminated cell
By employing a structure in perovskite solar cells where a first grain layer covers a second grain layer, and utilizing flash evaporation and antisolvent treatment to form a dense passivation layer, the problem of poor passivation film uniformity is solved, thereby improving photoelectric conversion efficiency and light absorption performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LONGI GREEN ENERGY TECH CO LTD
- Filing Date
- 2024-11-12
- Publication Date
- 2026-05-19
AI Technical Summary
In existing technologies, the passivation film of perovskite materials has poor uniformity, resulting in poor passivation effect and affecting the improvement of photoelectric conversion efficiency of perovskite solar cells.
The structure adopts a first grain layer covering a second grain layer, with the first grain layer in direct contact and covering the second grain layer, and the grain morphology is completely matched. The thickness of the first grain layer is smaller than that of the second grain layer. A dense passivation layer is formed through flash evaporation and anti-solvent treatment to protect and passivate the second grain layer.
It improves the photoelectric conversion efficiency of perovskite solar cells by more than 2%, protects the light absorption performance of the second grain layer, avoids the influence of the electrode layer, and enhances the passivation effect.
Smart Images
Figure CN122069883A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of solar cells, specifically to a perovskite solar cell and its preparation method, as well as a perovskite tandem solar cell including the perovskite solar cell. Background Technology
[0002] Perovskite solar cells are a type of solar cell that uses perovskite-type (PVSK) material as the light-absorbing layer. They offer advantages such as high photoelectric conversion efficiency, low cost, and good stability. In solar cells, passivation reduces non-radiative recombination and charge recombination, thereby improving the photoelectric conversion efficiency. In perovskite solar cells, passivation technology is typically used to passivate the perovskite material, thereby increasing the open-circuit voltage and short-circuit current density, and ultimately improving the photoelectric conversion efficiency of the perovskite solar cell.
[0003] However, the passivation film formed on perovskite materials in existing technologies suffers from poor uniformity, resulting in poor passivation performance and consequently, limited improvement in the photoelectric conversion efficiency of perovskite solar cells. Therefore, improving the passivation effect on perovskite materials is extremely important for the development of perovskite solar cells. Summary of the Invention
[0004] In view of this, this application provides a perovskite solar cell and a method for preparing the same, as well as a perovskite tandem solar cell including the perovskite solar cell.
[0005] According to a first aspect of this application, a perovskite solar cell is provided, including a substrate and a perovskite layer located on the substrate. The perovskite layer includes a first grain layer and a second grain layer, wherein the first grain layer is farther away from the substrate than the second grain layer, and the first grain layer is in direct contact with and covers the second grain layer.
[0006] In this embodiment, the perovskite layer includes a first grain layer that directly contacts and covers the second grain layer. This means the morphology of the grains in the two grain layers is perfectly matched. This structure allows the first grain layer to comprehensively and uniformly passivate the second grain layer, thereby improving the photoelectric conversion efficiency of the perovskite solar cell. Furthermore, the first grain layer covering the second grain layer protects the second grain layer from the influence of other layers, such as electrode layers, thereby improving the light absorption performance of the second grain layer and further enhancing the photoelectric conversion efficiency of the perovskite solar cell.
[0007] In some implementations, the thickness of the first grain layer is less than the thickness of the second grain layer.
[0008] In this implementation scheme, the thickness of the first grain layer is controlled to be less than that of the second grain layer. This not only protects and passivates the second grain layer, but also does not affect the light absorption performance of the second grain layer, thereby further improving the photoelectric conversion efficiency of the perovskite solar cell.
[0009] In some embodiments, the thickness of the first grain layer is 5%-25% of the thickness of the perovskite layer, preferably, the thickness of the first grain layer is ≤450nm.
[0010] In this embodiment, limiting the thickness of the first grain layer to the above-mentioned range not only further enhances the protection and passivation effect of the first grain layer on the second grain layer, but also does not affect the light absorption performance of the second grain layer, thereby further improving the photoelectric conversion efficiency of the perovskite solar cell, which is more than 2% higher than that of conventional perovskite solar cells.
[0011] In some implementations, the thickness of the perovskite layer is ≥700 nm, preferably 700-2000 nm.
[0012] In this embodiment, limiting the thickness of the perovskite layer to the above-mentioned range can prevent the subsequently deposited electrode layer from passing through the gap and causing a short circuit.
[0013] In some embodiments, the size of the grains in the first grain layer is smaller than the size of the grains in the second grain layer. Preferably, the size of the grains in the first grain layer is 50-300 nm, and preferably, the size of the grains in the second grain layer is 500-2000 nm.
[0014] In this embodiment, the size of the grains in the first grain layer is smaller than that in the second grain layer. This structure of small grains on top and large grains on the bottom allows the small grains to be packed more densely, which can fill the gaps between the large grains, reduce the defects caused by the edge dangling bonds of the large grains, and further improve the protection and passivation effect on the second grain layer, thereby further improving the photoelectric conversion efficiency of the perovskite solar cell.
[0015] In some embodiments, the general structural formula of the grains in the first grain layer is A'BX3, and the general structural formula of the grains in the second grain layer is ABX3, wherein A' is one or more combinations of ammonium ions and alkylguanidine ions, A is a monovalent cation, B is a divalent metal cation, and X is a monovalent anion.
[0016] In this embodiment, the first grain layer formed using the above-mentioned components can achieve a good passivation effect on the second grain layer, and the second grain layer formed using the above-mentioned components has good light absorption properties, thus enabling the perovskite solar cell to have excellent photoelectric conversion efficiency.
[0017] In some embodiments, the perovskite solar cell further includes a hole transport layer located between the substrate and the perovskite layer, and an electron transport layer and a metal electrode layer sequentially stacked on the perovskite layer. Perovskite solar cells with such a structure exhibit excellent photoelectric conversion efficiency.
[0018] According to a second aspect of this application, a perovskite tandem solar cell is provided, including the perovskite solar cell of the first aspect of this application, wherein the substrate is a crystalline silicon substrate.
[0019] Perovskite tandem solar cells, including the aforementioned perovskite cells, exhibit excellent photoelectric conversion efficiency, such as a smaller open-circuit voltage (Voc), a larger fill factor (FF), and a smaller short-circuit current density (Jsc).
[0020] In some implementations, the crystalline silicon substrate cell has a textured structure on one side, and the perovskite cell is formed conformally on the surface of the textured structure.
[0021] In this embodiment, the textured surface of the crystalline silicon substrate cell conforms to the grain structure of the perovskite layer of the perovskite cell, which can improve the absorption of incident light by the crystalline silicon substrate, thereby improving the photoelectric conversion efficiency of the tandem cell.
[0022] According to a third aspect of this application, a method for preparing a perovskite solar cell is provided, comprising: providing a substrate and forming a perovskite layer on the substrate, wherein the perovskite layer includes a first grain layer and a second grain layer, the first grain layer being farther away from the substrate than the second grain layer, the first grain layer being in direct contact with the second grain layer and covering the second grain layer.
[0023] The perovskite solar cell prepared by this method has the same technical features as the perovskite solar cell of the first aspect of this application, and can achieve the same technical effects, which will not be repeated here.
[0024] In some embodiments, forming a perovskite layer includes: 1) coating a precursor solution containing a first component and a second component onto the surface of a substrate to form a first film layer, wherein the solubility of the first component is less than the solubility of the second component; 2) treating the first film layer by a first flash evaporation process to form a surface-cured second film layer; 3) immersing the second film layer in an antisolvent to form a third film layer; 4) subjecting the third film layer sequentially to a second flash evaporation process and an annealing treatment to obtain a perovskite layer comprising a first grain layer and a second grain layer.
[0025] In this preparation method, the solubility of the first component is controlled to be less than that of the second component. This allows the first component, with lower solubility, to precipitate first through a flash evaporation process, forming a solidified surface layer. In subsequent steps, this surface layer can: ① serve as a protective layer for the perovskite wet film. During antisolvent treatment, because the protective layer contains less perovskite solvent, it can resist the damage of the perovskite wet film to the antisolvent, thus eliminating the concentric circle phenomenon during antisolvent treatment and ultimately obtaining a uniform large-area perovskite film; ② serve as a seed layer for the epitaxial growth of the second grain layer. Because the surface layer has small grains and a large distribution of small grains, it can induce the directional epitaxial growth of perovskite, increasing the grain size of the second grain layer, for example, increasing the grain size longitudinally; ③ serve as a surface passivation layer for the second grain layer. Since the subsequent second grain layer grows epitaxially on this passivation layer, it comprehensively and uniformly passivates the subsequently epitaxially grown second grain layer. Then, taking advantage of the aforementioned characteristics of the surface layer, a second grain layer is further formed under the induction of the antisolvent on the surface layer, thereby forming a perovskite layer.
[0026] This preparation method takes advantage of the disadvantages of flash evaporation, namely the preferential precipitation of components with relatively low solubility during flash evaporation, to form a solidified surface layer on the thick wet perovskite film, turning a disadvantage into an advantage. Combined with antisolvent, a perovskite layer with excellent performance is prepared.
[0027] In some implementations, the extraction rate in the first flash evaporation process is 5-100 m³ / h. 3 / s, with a duration of 10s-1000s.
[0028] In this embodiment, controlling the pumping rate and time in the flash evaporation process within the aforementioned range allows for control of the thickness of the first grain layer within the same range. This not only protects and passivates the second grain layer but also does not affect its light absorption performance. Furthermore, this mass ratio minimizes the amount of components remaining in the second grain layer that were used to form the first grain layer, thereby further enhancing the light absorption performance of the second grain layer. Attached Figure Description
[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other implementation schemes can be obtained based on these drawings without creative effort.
[0030] Figure 1 SEM images of the surface of a perovskite layer prepared according to some embodiments of this application are shown.
[0031] Figure 2 SEM images of the surface of a perovskite light-absorbing layer prepared using antisolvents in the prior art are shown.
[0032] Figure 3 SEM images of the side surfaces of perovskite layers prepared according to some embodiments of this application are shown.
[0033] Figure 4 SEM images of the surface of a perovskite light-absorbing layer prepared by flash evaporation in the prior art are shown.
[0034] Figure 5 A schematic diagram of a perovskite tandem solar cell according to some embodiments of this application is shown.
[0035] Figure 6 A schematic diagram of a method for preparing a perovskite layer according to some embodiments of this application is shown.
[0036] Figure 7 SEM images of the perovskite layer prepared in Example 3 of this application are shown.
[0037] Figure 8 SEM images of the perovskite layer prepared in Example 4 of this application are shown.
[0038] Figure 9 The SEM image of the perovskite film prepared in Comparative Example 1 of this application is shown.
[0039] Figure 10 The SEM image of the perovskite film prepared in Comparative Example 2 of this application is shown. Detailed Implementation
[0040] The present application will now be clearly and completely described in conjunction with its embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all of them. All other embodiments that can be obtained by those skilled in the art based on the embodiments in this application are within the scope of protection of this application.
[0041] Unless otherwise defined, 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.
[0042] In this application, all numerical values or ranges are modified by “about”, indicating that variations within a range of “±10%” of the numerical value or range are included in this application.
[0043] As mentioned above, in perovskite solar cells, the passivation effect of existing passivation technologies is often less than expected, thus affecting the improvement of the photoelectric conversion efficiency. Therefore, it is necessary to improve passivation technology to provide a perovskite solar cell with significantly improved photoelectric conversion efficiency.
[0044] Therefore, according to a first aspect of this application, a perovskite solar cell is provided, the perovskite solar cell including a substrate and a perovskite layer located on the substrate, the perovskite layer including a first grain layer and a second grain layer, the first grain layer being farther away from the substrate than the second grain layer, the first grain layer being in direct contact with the second grain layer and covering the second grain layer.
[0045] The substrate of a perovskite solar cell is typically a transparent conductive substrate, whose main function is to introduce sunlight and collect the generated current. Therefore, the substrate material can be any material with high light transmittance and good conductivity. In some embodiments, the substrate material is one or more combinations of indium tin oxide (ITO), indium tungsten oxide (IWO), and indium titanium oxide (ITiO). Of course, any other material known in the art, such as a glass substrate, can also be used; those skilled in the art can choose according to their needs, as long as the above requirements are met. In some embodiments, the substrate thickness is 1-20 nm.
[0046] The perovskite layer is the core component of a perovskite solar cell, responsible for absorbing incident photons and generating photogenerated carriers to efficiently convert light energy into electrical energy. In this application, the perovskite layer includes a first grain layer and a second grain layer. The first grain layer is farther from the substrate than the second grain layer, and the first grain layer is in direct contact with and covers the second grain layer.
[0047] It can be understood that the perovskite layer, including the first grain layer and the second grain layer, is a layer formed by perovskite material with an ABX3 structure, and can also be called the "first perovskite grain layer" and the "second perovskite grain layer" respectively. The first grain layer has a passivating effect on the second grain layer, so it can be used as a passivation layer for the second grain layer. Both the first grain layer and the second grain layer have light absorption effects.
[0048] Furthermore, in this perovskite layer, the first grain layer is in direct contact with and covers the second grain layer, meaning that the grain morphologies of the two grain layers are perfectly matched. This structure allows the first grain layer to passivate the second grain layer comprehensively and uniformly, thereby improving the photoelectric conversion efficiency of the perovskite solar cell.
[0049] Furthermore, the first grain layer covering the second grain layer can protect the second grain layer from the influence of other layers such as electrode layers, thereby improving the light absorption performance of the second grain layer and further improving the photoelectric conversion efficiency of the perovskite solar cell.
[0050] Figure 1 SEM images of the surface of a perovskite layer prepared according to some embodiments of this application are shown. It can be seen that the surface grains of the first grain layer in this perovskite layer are small, and there is a high distribution of small grains. The formation of such a surface grain layer is beneficial for inducing the directional epitaxial growth of perovskite and increasing the grain size of the second grain layer.
[0051] Figure 2 The image shows a SEM image of the surface of a perovskite absorbing layer prepared using an antisolvent in the prior art. It can be seen that the surface grains of the perovskite absorbing layer are relatively large, with a small number of small grains distributed throughout.
[0052] Figure 3 SEM images of the side surface of a perovskite layer prepared according to some embodiments of this application are shown. It can be seen that the perovskite layer exhibits a layering phenomenon, with the upper layer thinner than the lower layer. The thickness of the first grain layer is approximately 300 nm, and the thickness of the perovskite layer is approximately 1600 nm.
[0053] Figure 4 The image shows a SEM image of the surface of a perovskite light-absorbing layer prepared by flash evaporation in the prior art. It can be seen that the perovskite light-absorbing layer does not exhibit grain delamination; it consists entirely of continuous, vertically integrated grain layers.
[0054] In this application, the general structural formula of the first grain layer is A'BX3, and the general structural formula of the second grain layer is ABX3, wherein A' is an isoalkylammonium ion, ammonium ion (NH4+) + A is a monovalent cation, B is a divalent metal cation, and X is a monovalent anion.
[0055] For A', it can be understood that it is a monovalent cation, specifically, it can be an isoalkylammonium ion, an ammonium ion (NH4+), or an ammonium ion. + The alkylguanidine ion can be selected from one or more of the following: alkylguanidine ions, isoalkylammonium ions, isobutylammonium ions, etc. The alkylguanidine ion can be selected from one or more of the following: guanidine phosphate ions, guanidine hypophosphite ions, guanidine fluoride ions, and isobutylguanidine ions.
[0056] For A, it can be understood that it can be any monovalent inorganic or organic cation known in the art that can be used to form a perovskite light-absorbing layer, such as metal cations, alkylammonium ions, thiophene cations, imidazole cations, and pyridine cations. Specifically, the metal cation can be selected from Rb. + Cs +One or more combinations of alkylammonium ions, etc.; alkylammonium ions can be selected from C1-C18 alkylammonium salts, such as methanediamide ions, ethanediamide ions, propanediamide ions, butanediamide ions, pentanediamide ions, hexanediamide ions, heptanediamide ions, octanediamide ions, nonanediamide ions, decanediamide ions, undecanediamide ions, dodecanediamide ions, tridecanediamide ions, tetradecanediamide ions, pentadecanediamide ions, hexadecanediamide ions, heptanediamide ions, octadecanediamide ions, and their isomers, etc. One or more combinations thereof; thiophene cations may be selected from one or more combinations of 2-thiopheneformamidin ion, 2-thiophenemethylamine ion, 2-thiopheneethylamine ion, 2-thiopheneformamidin ion, etc.; imidazole cations may be selected from one or more combinations of 2-imidazolium methylamine ion, 2-imidazoliumformamidin ion, 2-imidazoliumethylamine ion, 2-imidazoliumbutylamine ion, etc.; pyridine cations may be selected from one or more combinations of 2-pyridinemethylamine ion, 2-pyridineformamidin ion, 2-thiopheneethylamine ion, 2-thiopheneethylamidin ion, etc. In some embodiments, A is formamidin ion (FA). + ), methylammonium ion (MA) + Cs ions (Cs + One or more combinations of )
[0057] For B, it is understood that it can be any divalent metal cation known in the art that can be used to form a perovskite light-absorbing layer. Specifically, B can be selected from Cu. 2+ Ni 2+ Co 2+ Fe 2+ Mn 2+ Cr 2+ Pd 2+ Cd 2+ 、Ge 2+ Sn 2+ Pb 2+ Eu 2+ Yb 2+ One or more of the following combinations.
[0058] For X, it is understood that it can be any monovalent anion known in the art that can be used to form a perovskite light-absorbing layer, such as a halide anion or a halide-like anion. Specifically, the halide anion can be selected from I. - ,Br - Cl -One or more combinations of these. For halogen-like substances, as understood by those skilled in the art, this refers to certain atomic groups that, in their free state, are similar in properties to elemental halogens (see halogen groups), and whose anions are also similar to halide ions, such as cyanide (CN)₂, thiocyanate (SCN)₂, selenocyanate (SeCN)₂, oxocyanate (OCN)₂, and carbon azide disulfide (SCSN₃)₂. Azide ion N₃ - and telluride cyanate ion TeCN - Similar to halide ions, but lacking a corresponding parent substance for elemental halogens, they are called halide-like ions. Halide-like anions can be selected from CN... - SCN - One or more of the following combinations.
[0059] The first grain layer formed using the above components can effectively passivate the second grain layer, and the second grain layer formed using the above components has excellent light absorption properties, thus enabling the perovskite solar cell to have excellent photoelectric conversion efficiency.
[0060] In some embodiments, the thickness of the first grain layer is less than the thickness of the second grain layer. In this application, the thickness of the first grain layer refers to its maximum thickness in the direction perpendicular to the surface of the perovskite layer, i.e., the thickness from the lowest point of the grain to the surface of the perovskite layer. The thickness of the second grain layer refers to its maximum thickness in the direction perpendicular to the surface of the perovskite layer. Controlling the thickness of the first grain layer to be less than the thickness of the second grain layer not only achieves protection and passivation of the second grain layer but also does not affect its light absorption performance, thereby further improving the photoelectric conversion efficiency of the perovskite solar cell.
[0061] In this application, the thickness of the perovskite layer refers to the maximum thickness of the perovskite layer in the direction perpendicular to its surface. It can also be understood as the thickness of the perovskite layer from the bottom of the pyramid structure of the substrate to the surface of the perovskite layer in the direction perpendicular to its surface; it can also be referred to as the first thickness of the perovskite layer. Unless otherwise specified, the thickness of the perovskite layer in this application refers to the first thickness of the perovskite layer.
[0062] In some embodiments, the thickness of the first grain layer is 5%-25% of the thickness of the perovskite layer, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%. In a preferred embodiment, the thickness of the first grain layer is 20% of the thickness of the perovskite layer. In a preferred embodiment, the thickness of the first grain layer is ≤450 nm, for example, 30, 50, 80, 100, 150, 200, 250, 300, 350, 400, 450 nm.
[0063] By limiting the thickness of the first grain layer to the above range, not only can the second grain layer be protected and passivated, but the light absorption performance of the second grain layer will not be affected, thereby further improving the photoelectric conversion efficiency of the perovskite solar cell.
[0064] In some embodiments, the thickness of the perovskite layer is ≥700 nm, for example, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, or 2500 nm. Limiting the thickness of the perovskite layer within this range prevents the subsequently deposited electrode layer from penetrating the gap and causing a short circuit. In a preferred embodiment, the thickness of the perovskite layer is 700-2000 nm. Controlling the thickness of the perovskite layer within this range further improves the aforementioned performance.
[0065] In some embodiments, the thickness of the perovskite layer can also be understood as the thickness of the perovskite layer from the apex of the pyramid structure of the substrate to the surface of the perovskite layer in a direction perpendicular to the surface of the perovskite layer; this thickness is referred to as the second thickness of the perovskite layer. In some embodiments, the second thickness of the perovskite layer is ≥400 nm, for example, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, or 2000 nm. In preferred embodiments, the thickness of the perovskite layer is 400-1700 nm. Limiting the second thickness of the perovskite layer to the above range can prevent the subsequently deposited electrode layer from penetrating the gap and causing a short circuit.
[0066] In some embodiments, the size of the grains in the first grain layer is smaller than the size of the grains in the second grain layer. As understood by those skilled in the art, grain size refers to the size of the grains within a crystal. In this application, grain size refers to the edge length, diagonal length, diameter, etc., of the grain. It is understood that the aforementioned dimensions of the first grain layer are all smaller than the corresponding dimensions of the second grain layer.
[0067] By controlling the size of the grains in the first grain layer to be smaller than that in the second grain layer, this structure of small grains on top and large grains on the bottom allows the small grains to be packed more densely, filling the gaps between the large grains and reducing defects caused by dangling bonds at the edges of the large grains. This further enhances the protection and passivation of the second grain layer, thereby further improving the photoelectric conversion efficiency of the perovskite solar cell.
[0068] In a preferred embodiment, the grain size of the first grain layer is 50-300 nm, for example, 50, 60, 70, 80, 90, 100, 150, 200, 250, or 300 nm. Preferably, the grain size of the second grain layer is 500-2000 nm, for example, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, or 2000 nm. Controlling the grain size of the first and second grain layers within the above ranges can further improve the aforementioned performance.
[0069] In some embodiments, the perovskite solar cell further includes a hole transport layer (HTL) located between the substrate and the perovskite layer, and an electron transport layer and a metal electrode layer sequentially stacked on the perovskite layer. Perovskite solar cells with such a structure exhibit excellent photoelectric conversion efficiency.
[0070] In some embodiments, the perovskite solar cell further includes an electron transport layer located between the substrate and the perovskite layer, and a hole transport layer and a metal electrode layer sequentially stacked on the perovskite layer. Perovskite solar cells with such a structure exhibit excellent photoelectric conversion efficiency.
[0071] As understood by those skilled in the art, the primary function of the hole transport layer is to extract and transport photogenerated holes and suppress hole backflow, thereby improving the photoelectric conversion efficiency of perovskite solar cells. Therefore, the material of the hole transport layer can be any material capable of effectively extracting and transporting photogenerated holes. In some embodiments, the material of the hole transport layer includes (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid (MeO-2PACz), (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz), (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACz), self-assembled molecular layers (SAMs), etc. Of course, any other material known in the art that can be used for the hole transport layer can also be used; those skilled in the art can choose according to their needs, as long as the above requirements are met.
[0072] As those skilled in the art understand, the primary function of the electron transport layer is to transport electrons and suppress electron backflow, thereby improving the photoelectric conversion efficiency of the perovskite solar cell. Therefore, the material of the electron transport layer can be any material with good electron mobility and stability, capable of transporting electrons generated in the perovskite layer to the substrate. In some embodiments, the electron transport layer material includes titanium dioxide (TiO2), zinc oxide (ZnO), etc., or it can be a combination of aluminum oxide (Al2O3) or lithium fluoride with organic materials such as C60, PCBM, etc. (this can be prepared by vapor deposition of an organic material such as C60, PCBM, etc., onto an Al2O3 or lithium fluoride film). Of course, any other material known in the art for use in the electron transport layer can also be used; those skilled in the art can choose according to their needs, as long as the above requirements are met.
[0073] In some embodiments, the perovskite solar cell further includes an electrode layer located on the electron transport layer. This electrode layer comprises metal electrodes, whose primary function is to transport charge and connect to external circuits. Specifically, the metal electrodes collect photogenerated carriers through the electron and hole transport layers, enabling the charge to be smoothly discharged from the cell and connected to the external circuit. Therefore, the electrode layer can be made of any material with conductive properties. In some embodiments, the electrode layer is made of one or more combinations of gold, silver, or aluminum. Of course, any other material known in the art for use with metal electrodes can also be used; those skilled in the art can choose according to their needs, as long as the above requirements are met.
[0074] In some embodiments, the electrode layer further includes a buffer layer located between the electron transport layer and the metal electrode. As those skilled in the art will understand, the primary function of the buffer layer is to prevent perovskite from corroding the metal electrode and to prevent metal migration into the perovskite layer and transport layer, thereby preventing device performance degradation. Therefore, the buffer layer can be made of any material capable of effectively blocking ion migration. In some embodiments, the buffer layer is made of ZnO or SnO. 2、 One or more of TiO2 and other materials are acceptable. Of course, any other material known in the art for use in buffer layers can also be used, and those skilled in the art can choose as needed, as long as the above requirements are met. In some embodiments, the thickness of the buffer layer is 10-20 nm.
[0075] In some embodiments, the electrode layer further includes a transparent conductive layer located on the buffer layer, which can be formed using the same material as the transparent conductive substrate and has the same technical effects as the transparent conductive substrate. In some embodiments, the thickness of the transparent conductive layer is 1-200 nm.
[0076] In some embodiments, the electrode layer further includes an antireflection film layer located on the transparent conductive layer. Its main function is to reduce light reflection loss and increase light absorption, thereby improving the photoelectric conversion efficiency of the battery. Therefore, the material of the antireflection film layer can be any material known in the art for reducing light reflection, and this application will not further describe this.
[0077] According to a second aspect of this application, a perovskite tandem solar cell is provided, including the perovskite solar cell of the first aspect of this application, wherein the substrate is a crystalline silicon substrate.
[0078] In this application, the substrate of the crystalline silicon substrate cell can be monocrystalline silicon or polycrystalline silicon.
[0079] Perovskite tandem solar cells, including the perovskite solar cells mentioned above, have excellent photoelectric conversion efficiency, such as a small open-circuit voltage (Voc) and a large fill factor (FF).
[0080] In some implementations, the crystalline silicon substrate cell has a textured structure on one side, and the perovskite cell is formed conformally on the surface of the textured structure.
[0081] In this embodiment, the textured surface of the crystalline silicon substrate cell conforms to the grain structure of the perovskite layer of the perovskite cell, which can improve the absorption of incident light by the crystalline silicon substrate, thereby improving the photoelectric conversion efficiency of the tandem cell.
[0082] Figure 5 A schematic diagram of a perovskite tandem solar cell according to some embodiments of this application is shown, wherein 100 is a commercial-grade M2 n-silicon wafer solar cell; 200 is a perovskite solar cell, wherein 102 is a transparent conductive material (TCO) layer, 201 is a hole transport layer, 203 is the perovskite layer of this application, 204 is an electron transport layer, 205 is a buffer layer, 206 is a TCO layer, 103 is a metal electrode, and 207 is an antireflection coating layer.
[0083] According to a third aspect of this application, a method for preparing a perovskite solar cell is provided, comprising: providing a substrate and forming a perovskite layer on the substrate, wherein the perovskite layer includes a first grain layer and a second grain layer, the first grain layer being farther away from the substrate than the second grain layer, the first grain layer being in direct contact with the second grain layer and covering the second grain layer.
[0084] The perovskite solar cell prepared by this method has the same technical features as the perovskite solar cell of the first aspect of this application, and can achieve the same technical effect, which will not be repeated here.
[0085] In some embodiments, the steps of forming the perovskite layer include: 1) coating a precursor solution containing a first component and a second component onto the surface of a substrate to form a first film layer, wherein the solubility of the first component is less than the solubility of the second component; 2) treating the first film layer by a first flash evaporation process to form a surface-cured second film layer; 3) immersing the second film layer in an antisolvent to form a third film layer; 4) sequentially passing the third film layer through a second flash evaporation process and an annealing treatment to obtain a perovskite layer comprising a first grain layer and a second grain layer.
[0086] It can be understood that the first component is the perovskite material used to form the first grain layer, which can also be called the first perovskite component, and the second component is the perovskite material used to form the second grain layer, which can also be called the second perovskite component.
[0087] In step 1), the precursor solution is formed by mixing a first precursor solution containing a first component and a second precursor solution containing a second component, wherein the first component has the general structural formula A'BX3 and the second component has the general structural formula ABX3.
[0088] In some embodiments, the solvent in the precursor solution can be one or a combination of two of DMF and DMSO. Of course, other solvents commonly used in the art can also be used, and this application does not limit this.
[0089] Furthermore, the solubility of the first component is less than the solubility of the second component. In some embodiments, the solubility of the second component is 90-105 times that of the first component, for example, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, or 105 times, preferably 100 times.
[0090] In some embodiments, the molar amount of the first component accounts for 0.1%-30% of the total molar amount of the first and second components, for example, 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, and 30%. It is understood that the higher the molar content of the perovskite component, the greater the thickness of the resulting grain layer. In some embodiments, the thickness of the first grain layer is 30-50 nm; in some embodiments, the thickness of the first grain layer is 50-200 nm; and in some embodiments, the thickness of the first grain layer is 200-450 nm.
[0091] In step 1), the precursor solution can be coated onto the surface of the substrate by any method known in the art, such as spin coating, thereby forming a perovskite wet film, i.e., the first film layer, on the substrate.
[0092] In step 2), the first flash evaporation process causes only the solvent in the surface layer of the first film layer to vaporize and evaporate, while the solvent below does not evaporate, thereby forming a surface-cured perovskite semi-dry film, i.e., the second film layer.
[0093] In step 3), immersing the second film layer in the antisolvent allows the remaining solvent in the film layer to be extracted to the surface of the second film layer, thereby forming a perovskite dry film, i.e., the third film layer.
[0094] As those skilled in the art will understand, an antisolvent is a solvent miscible with respect to a specific solution system, meaning a solvent that is insoluble in the solvent but cannot dissolve the solute. In step 3), the antisolvent used is a type of solvent that can dissolve the perovskite precursor solution but not the perovskite component, such as ethyl acetate or diethyl ether. Of course, other antisolvents known in the art can also be used, as long as they meet the above requirements.
[0095] In step 4), the third film layer is treated by a second flash evaporation process to remove the antisolvent and residual solvent, and then annealed to fuse the small grains into large grains, thereby forming a perovskite layer including the first grain layer and the second grain layer.
[0096] It can be seen that the second flash evaporation process is mainly used to remove antisolvents and residual solvents. This application does not further limit the specific parameters, as long as the above requirements can be met.
[0097] Figure 6 A schematic diagram of a method for preparing a perovskite layer according to some embodiments of this application is shown.
[0098] In this preparation method, the solubility of the first component is controlled to be less than that of the second component. This allows the first component, with lower solubility, to precipitate first through a flash evaporation process, thereby forming a solidified surface layer. This surface layer can, in subsequent steps, ① serve as a protective layer for the perovskite wet film beneath it. During antisolvent treatment, because the protective layer contains less perovskite solvent, it can resist the damage of the large-area perovskite wet film to the antisolvent, thus eliminating the concentric circle phenomenon during antisolvent treatment of the large-area perovskite wet film and ultimately obtaining a uniform large-area perovskite film; ② serve as a seed layer for the epitaxial growth of the second grain layer. Because the surface layer has small grains and a large distribution of small grains, it can induce the directional epitaxial growth of perovskite, increasing the grain size of the second grain layer, for example, increasing the grain size longitudinally; ③ serve as a surface passivation layer for the second grain layer. Since the subsequent second grain layer grows epitaxially on this passivation layer, the passivation layer comprehensively and uniformly passivates the subsequently epitaxially grown second grain layer. Then, taking advantage of the aforementioned characteristics of the surface layer, a second grain layer is further formed on the surface layer under the induction of the antisolvent, thereby forming a perovskite layer.
[0099] This preparation method takes advantage of the disadvantages of flash evaporation, namely the preferential precipitation of components with relatively low solubility during flash evaporation, to form a solidified surface layer on the thick wet perovskite film, turning a disadvantage into an advantage. Combined with antisolvent, a perovskite layer with excellent performance is prepared.
[0100] In some implementations, the extraction rate in the first flash evaporation process is 5-100 m³ / h. 3 / s, for example 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100m 3 / s. The evacuation time in the first flash evaporation process is 10s-1000s, for example 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000.
[0101] By controlling the pumping rate and time in the flash evaporation process within the aforementioned range, the thickness of the first grain layer can be controlled within the same range. This not only protects and passivates the second grain layer but also does not affect its light absorption performance. Furthermore, this mass ratio minimizes the amount of components remaining in the second grain layer that were used to form the first grain layer, thereby further improving the light absorption performance of the second grain layer.
[0102] The present application will now be described in more detail with reference to the accompanying drawings and embodiments. These embodiments are merely preferred embodiments of the present application and are not intended to limit the scope of the application. Unless otherwise specified, all raw materials and reagents used in this application are commercially available.
[0103] Example
[0104] Example 1
[0105] Fabrication of crystalline silicon / perovskite tandem solar cells
[0106] 1) Provide crystalline silicon substrate cells.
[0107] 2) A hole transport layer was prepared on a crystalline silicon substrate solar cell by spin coating.
[0108] 3) Fabrication of a perovskite layer on the hole transport layer: The perovskite layer is fabricated through the following steps:
[0109] ① Preparation of perovskite precursor solution: Dissolve the first component A'BX3 (A'X and BX2 in a molar ratio of 1:1) in DMF to obtain the first perovskite precursor solution, wherein A' is isopropylamine ion (iso-PA). + B is Pb 2+ X is I- The second component ABX3 (AX and BX2 in a molar ratio of 1:1) was dissolved in the solvent DMF to obtain a second perovskite precursor solution, wherein A is a formamidinium cation (FA). + ) and methylamine cation (MA + B is Pb 2+ X is I - 100 μL of a 0.1 mol / mL first precursor solution was added to 1 mL of a 1 mol / mL second precursor solution and mixed thoroughly to obtain a perovskite precursor solution. It can be seen that in the perovskite precursor solution,
[0110] The molar ratio of the first component to the second component is 1:100;
[0111] ② The perovskite precursor solution is coated onto the textured surface of the crystalline silicon substrate cell by spin coating to form the first film layer;
[0112] ③ The first film layer is treated by the first flash evaporation process to form a second film layer with surface curing;
[0113] ④ Immerse the second film layer in the antisolvent to form the third film layer;
[0114] ⑤ The third film layer is treated by a second flash evaporation process and then annealed to obtain the perovskite layer.
[0115] 4) An electron transport layer was prepared on the perovskite layer by spin coating.
[0116] 5) Prepare metal electrodes on the electron transport layer by vacuum evaporation.
[0117] Example 2
[0118] The difference between Example 2 and Example 1 is that in the precursor solution, A' is isobutylamine ions (iso-BA). + ).
[0119] Example 3
[0120] The difference between Example 3 and Example 1 is that in the preparation of the perovskite layer, 500 μL of 0.1 mol / mL first precursor solution is added to 1 mL of 1 mol / mL second precursor solution and mixed evenly to obtain a perovskite precursor solution. It can be seen that in the perovskite precursor solution, the molar ratio of the first component to the second component is 5:100.
[0121] Figure 7 SEM images of the perovskite layer prepared in Example 3 are shown. It can be seen that the thickness of the first grain layer is about 90 nm, and the thickness of the second grain layer is about 1200 nm.
[0122] Example 4
[0123] The difference between Example 4 and Example 1 is that in the preparation of the perovskite layer, 1000 μL of 0.1 mol / mL first precursor solution is added to 1 mL of 1 mol / mL second precursor solution and mixed evenly to obtain a perovskite precursor solution. It can be seen that in the perovskite precursor solution, the molar ratio of the first component to the second component is 1:10.
[0124] Figure 8 SEM images of the perovskite layers prepared in Example 4 are shown. It can be seen that the thickness of the first grain layer is approximately 150 nm, and the thickness of the second grain layer is approximately 600 nm.
[0125] Example 5
[0126] The difference between Example 5 and Example 1 is that in the preparation of the perovskite layer, 2000 μL of 0.1 mol / mL first precursor solution is added to 1 mL of 1 mol / mL second precursor solution and mixed evenly to obtain a perovskite precursor solution. It can be seen that in the perovskite precursor solution, the molar ratio of the first component to the second component is 2:10.
[0127] Example 6
[0128] The difference between Example 6 and Example 1 is that in the first perovskite precursor solution, A' is guanidinium phosphate ions and B is Pb. 2+ X is I - In the second perovskite precursor solution, A is methanethiamine ion and B is Pb. 2+ X is I - In the preparation of the perovskite layer, 1000 μL of 0.1 mol / mL first precursor solution was added to 1 mL of 1 mol / mL second precursor solution and mixed evenly to obtain a perovskite precursor solution. It can be seen that in the perovskite precursor solution, the molar ratio of the first component to the second component is 1:10.
[0129] Example 7
[0130] The difference between Example 1 and Example 2 is that in the first perovskite precursor solution, A' is guanidine fluoride ion and B is Pb. 2+ X is I - In the second perovskite precursor solution, A is Rb + B is Pb 2+ X is I -In the preparation of the perovskite layer, 100 μL of 0.1 mol / mL first precursor solution was added to 1 mL of 1 mol / mL second precursor solution and mixed evenly to obtain a perovskite precursor solution. It can be seen that in the perovskite precursor solution, the molar ratio of the first component to the second component is 1:100.
[0131] Comparative Example 1
[0132] The difference between Comparative Example 1 and Example 1 is that in the preparation process of the perovskite layer, the perovskite precursor solution is a second perovskite precursor solution, that is, the formed perovskite layer does not include the first grain layer as a passivation layer. The molar concentration of the second precursor solution is 1 mol / mL and the volume is 1 mL. Figure 9 The SEM image of the perovskite film prepared in Comparative Example 1 is shown.
[0133] Comparative Example 2
[0134] The difference between Comparative Example 2 and Example 1 is that the perovskite light-absorbing layer is formed using the flash evaporation process in the prior art, and then a passivation layer is prepared by coating process. Specifically, 2D / 1D amine salt and macromolecular organic ligand are first dissolved in solvent to prepare 2D / 1D amine salt solution and macromolecular organic ligand solution. Finally, the solution is coated on the surface of the pre-prepared perovskite light-absorbing layer, and after annealing and drying, a passivation layer is formed. Figure 10 The SEM image of the perovskite film prepared in Comparative Example 2 is shown.
[0135] The open-circuit voltage (VOC), short-circuit current density (Jsc), fill factor (FF), and photoelectric conversion efficiency (PCE) of the tandem cells in the examples and comparative examples were tested respectively, and the results are shown in Table 1 below.
[0136] Table 1
[0137]
[0138]
[0139] As can be seen from the test results in Table 1, the Voc, FF, and Jsc of the tandem solar cell including the perovskite light-absorbing layer of this application are increased, and the photoelectric conversion efficiency is significantly increased, specifically, by at least 2%.
Claims
1. A perovskite solar cell, characterized in that, The device includes a substrate and a perovskite layer on the substrate. The perovskite layer includes a first grain layer and a second grain layer. The first grain layer is farther away from the substrate than the second grain layer. The first grain layer is in direct contact with the second grain layer and covers the second grain layer.
2. The perovskite solar cell according to claim 1, characterized in that, The thickness of the first grain layer is less than the thickness of the second grain layer. Preferably, the thickness of the first grain layer is 5%-25% of the thickness of the perovskite layer. More preferably, the thickness of the first grain layer is ≤450nm.
3. The perovskite solar cell according to claim 1, characterized in that, The thickness of the perovskite layer is ≥700nm, preferably 700-2000nm.
4. The perovskite solar cell according to claim 1, characterized in that, The size of the grains in the first grain layer is smaller than the size of the grains in the second grain layer. Preferably, the size of the grains in the first grain layer is 50-300 nm, and preferably, the size of the grains in the second grain layer is 500-2000 nm.
5. The perovskite solar cell according to claim 1, characterized in that, The general structural formula of the first grain layer is A'BX3, and the general structural formula of the second grain layer is ABX3, wherein A' is one or more combinations of ammonium ions and alkylguanidine ions, A is a monovalent cation, B is a divalent metal cation, and X is a monovalent anion.
6. The perovskite solar cell according to claim 1, characterized in that, The perovskite solar cell further includes a hole transport layer located between the substrate and the perovskite layer, and an electron transport layer and a metal electrode layer sequentially stacked on the perovskite layer.
7. A perovskite tandem solar cell, characterized in that, The perovskite solar cell includes any one of claims 1-6, wherein the substrate is a crystalline silicon substrate.
8. The perovskite tandem solar cell according to claim 7, characterized in that, The crystalline silicon substrate cell has a textured surface on one side, and the perovskite cell is formed conformally on the surface of the textured surface.
9. A method for preparing a perovskite solar cell, characterized in that, include: A substrate is provided on which a perovskite layer is formed, wherein the perovskite layer includes a first grain layer and a second grain layer, the first grain layer being more distant from the substrate than the second grain layer, the first grain layer being in direct contact with and covering the second grain layer.
10. The preparation method according to claim 9, characterized in that, The formation of the perovskite layer includes: 1) A precursor solution containing a first component and a second component is coated onto the surface of the substrate to form a first film layer, wherein the solubility of the first component is less than the solubility of the second component; 2) The first film layer is treated by a first flash evaporation process to form a second film layer with surface curing; 3) Immerse the second film layer in the antisolvent to form the third film layer; 4) The third film layer is sequentially subjected to a second flash evaporation process and an annealing process to obtain the perovskite layer comprising the first grain layer and the second grain layer.