Method for forming textured surface of cell, and tandem cell and preparation method therefor

Abstract

Provided in the present application are a method for forming a textured surface of a cell, and a tandem cell and a preparation method therefor. The method for forming a textured surface of a cell comprises the following steps: providing a crystalline silicon substrate; performing a first texturing treatment on the crystalline silicon substrate to form a first pyramidal textured surface on the top of the crystalline silicon substrate, wherein the height of the first pyramidal textured surface is a first height; by means of ozone and hydrofluoric acid, performing a first rounding treatment on the first pyramidal textured surface; by means of nitric acid and hydrofluoric acid, performing a second rounding treatment on the first pyramidal textured surface; and performing a second texturing treatment on the crystalline silicon substrate to form a second pyramidal textured surface, wherein the height of the second pyramidal textured surface is a second height, and the second height is less than the first height.

Description

Methods for forming textured surfaces of batteries, stacked batteries and their fabrication methods

[0001] Related applications

[0002] This application claims priority to Chinese patent application filed on January 14, 2025, with application number 2025100602254, entitled "Method for forming textured surface of battery, stacked battery and preparation method thereof", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of photovoltaic technology, and in particular to a method for forming a textured surface of a battery, a tandem battery, and a method for preparing the same. Background Technology

[0004] Perovskite-silicon tandem solar cells are a structure that combines crystalline silicon solar cells with perovskite solar cells. Through complementary advantages and synergistic effects, the conversion efficiency is improved, and it is considered to be the next generation of mass-produced photovoltaic technology.

[0005] In traditional techniques, to achieve conformal fabrication of perovskite thin films on textured silicon surfaces, two-step processes involving dry evaporation followed by wet reaction, dry co-evaporation, or a one-step wet process can be used. The wet process can complete the fabrication in a single step. The wet process involves first dissolving the organic and inorganic salts of the perovskite material components in a solvent to prepare a precursor solution. This precursor solution is then applied to a substrate using methods such as spin coating, blade coating, or slot coating. Finally, the perovskite thin film is formed through flash evaporation and annealing.

[0006] However, the large textured surface of crystalline silicon is generally a pyramidal surface with low surface energy. During the wet process, it is difficult for the perovskite wet film to completely cover the pyramid tip in a conformal manner. Summary of the Invention

[0007] According to various embodiments of this application, a method for forming a textured surface of a battery, a stacked battery, and a method for preparing the same are provided.

[0008] In a first aspect, this application provides a method for forming a textured surface on a battery, comprising the following steps: providing a crystalline silicon substrate; performing a first texturing process on the crystalline silicon substrate to form a first pyramidal textured surface on the top of the crystalline silicon substrate; the height of the first pyramidal textured surface being a first height; performing a first rounding process on the first pyramidal textured surface using ozone and hydrofluoric acid; performing a second rounding process on the first pyramidal textured surface using nitric acid and hydrofluoric acid; performing a second texturing process on the crystalline silicon substrate to form a second pyramidal textured surface; the height of the second pyramidal textured surface being a second height, the second height being less than the first height.

[0009] In one embodiment, the first height is 4 μm to 6 μm.

[0010] In one embodiment, the second height is 0.1 μm to 0.4 μm.

[0011] In one embodiment, the concentration of ozone introduced during the first rounding process is 10 ppm to 60 ppm.

[0012] In one embodiment, the mass concentration of hydrofluoric acid in the first rounding treatment is 30% to 60%.

[0013] In one embodiment, the total processing time for the first rounding process is 60s to 180s.

[0014] In one embodiment, the mass concentration of nitric acid in the second rounding treatment is 2% to 30%.

[0015] In one embodiment, the mass concentration of nitric acid in the second rounding treatment is 2% to 15%.

[0016] In one embodiment, the mass concentration of hydrofluoric acid in the second rounding treatment is 0.5% to 5%.

[0017] In one embodiment, the total processing time for the second rounding process is 60s to 180s.

[0018] In one embodiment, the first rounding process forms an arc with a radius of not less than 0.8 μm at the top of the first pyramid textured surface.

[0019] In one embodiment, the second rounding process involves forming an arc with a radius of not less than 0.8 μm at the base of the first pyramid textured surface.

[0020] Secondly, this application also provides a method for preparing a tandem solar cell, comprising the following steps: providing a crystalline silicon substrate; performing a first texturing process on the crystalline silicon substrate to form a first pyramidal textured surface on the top of the crystalline silicon substrate; the height of the first pyramidal textured surface being a first height; performing a first rounding process on the first pyramidal textured surface using ozone and hydrofluoric acid; performing a second rounding process on the first pyramidal textured surface using nitric acid and hydrofluoric acid; performing a second texturing process on the crystalline silicon substrate to form a second pyramidal textured surface; the height of the second pyramidal textured surface being a second height, the second height being less than the first height; forming a perovskite thin film solution on the crystalline silicon substrate, and drying to obtain a tandem solar cell.

[0021] Thirdly, this application also provides a stacked battery, the stacked battery comprising: a crystalline silicon substrate, the upper surface of the crystalline silicon substrate defining a first pyramidal textured surface, the top and bottom of the first pyramidal textured surface being at least partially arcuate structures, the arcuate structures defining a second pyramidal textured surface, the second height of the second pyramidal textured surface being less than the first height of the first pyramidal textured surface; and a perovskite thin film conformally covering the upper surface of the crystalline silicon substrate.

[0022] In one embodiment, the first height of the first pyramid textured surface is 4μm to 6μm.

[0023] In one embodiment, the second height of the second pyramid textured surface is 0.1 μm to 0.4 μm.

[0024] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the disclosed drawings without creative effort.

[0026] Figure 1 is a schematic flowchart of a battery textured surface forming method according to one embodiment.

[0027] Figure 2 is a schematic diagram of forming a first pyramidal textured surface on a crystalline silicon substrate in one embodiment.

[0028] Figure 3 is a schematic diagram of the first and second rounding processes in one embodiment.

[0029] Figure 4 is a schematic diagram of the second texturing process in one embodiment.

[0030] Figure 5 is a schematic flowchart of a method for preparing a stacked battery in one embodiment. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] Perovskite-silicon tandem solar cells are poised to become the next generation of mass-produced photovoltaic technology due to their excellent conversion efficiency and low cost. Typically, to achieve conformal perovskite film fabrication on a textured surface, a two-step process is used: dry evaporation (co-evaporation of single or multiple metal halides such as PbI2, PbBr2, and CsBr) followed by a wet reaction (dissolving organic halides such as FAI and MACl in alcohol solvents); or dry co-evaporation (PbI2, PbBr2, CsI, CsBr, FAI, and MACl). However, both the dry evaporation-wet reaction and dry co-evaporation processes have drawbacks, including high equipment costs, low production reliability, and the lack of self-limiting perovskite composition, leading to low yield, low conversion efficiency, and poor stability in tandem solar cell production. Therefore, a more reliable perovskite film deposition process is urgently needed for the fabrication of tandem solar cells.

[0033] One approach is to use a one-step wet coating process. However, wet coating processes have extremely high requirements for the morphology of the crystalline silicon surface, requiring a relatively uniform distribution of high surface energy across the entire surface. The textured surface of crystalline silicon is typically a pyramidal surface, with a base angle of approximately 54 degrees and a base width of approximately 2μm to 4μm. Due to its sharp apex, the surface energy is relatively low, making it difficult for the perovskite wet film to completely conformally cover the pyramid apex during the wet coating process. Secondly, because the base of the pyramid is relatively narrow and has high surface energy, the solvent cannot completely fill the area at the base of the pyramid during the wet coating process, resulting in localized voids that affect charge transport and the mechanical adhesion between the films.

[0034] Referring to Figure 1, Figure 1 shows a schematic flowchart of a battery textured surface forming method in one embodiment. In some embodiments, the battery textured surface forming method includes the following steps:

[0035] S11 provides a crystalline silicon substrate 10.

[0036] S12, a first texturing process is performed on the crystalline silicon substrate 10 to form a first pyramidal textured surface 11 on the top of the crystalline silicon substrate 10; the height of the first pyramidal textured surface 11 is a first height H1. As shown in Figure 2, Figure 2 shows a schematic diagram of forming a first pyramidal textured surface 11 on a crystalline silicon substrate in some embodiments.

[0037] For example, before performing the first texturing process on the crystalline silicon substrate 10, the crystalline silicon substrate 10 can be pre-cleaned using a cleaning solution. Optionally, the cleaning solution can be water or the like.

[0038] For example, the first texturing process can use a commercial texturing agent and be etched using an alkaline solution.

[0039] S13, the first pyramid textured surface 11 is subjected to a first rounding treatment using ozone and hydrofluoric acid. As shown in Figure 3, Figure 3 is a schematic diagram of the first and second rounding treatments of crystalline silicon in one embodiment.

[0040] The apex region of the pyramid has a low surface energy due to its sharp features. In the texturing process of crystalline silicon, the etching rate of the Si(100) crystal plane is more than ten times greater than that of the Si(111) crystal plane. Therefore, the texturing process forms a pyramid structure. However, in some cases, the size of the first pyramid textured surface 11 is too large to maximize the reduction of surface energy. Here, "100" and "111" represent the crystal plane index of the Si surface.

[0041] For example, the top of the first pyramid velvet surface 11 refers to its top tip position. By performing a first rounding treatment on its top tip, a portion of the tip can be removed to form a rounded corner at the top of the first pyramid velvet surface.

[0042] In this step, ozone and hydrofluoric acid are used for combined etching. This step prioritizes etching the top region of the pyramid to round the top of the first pyramid, thereby exposing the Si(100) crystal plane of the crystalline silicon substrate. The Si(100) crystal plane is flatter and has a higher surface energy than the Si(111) crystal plane, which facilitates the subsequent second texturing process and is beneficial for the conformal coverage of the subsequent perovskite thin film.

[0043] Specifically, ozone is introduced into a weakly acidic solution. After stabilization, the crystalline silicon substrate 10 treated in step S12 is placed in the mixed solution and treated for a period of time. The silicon at the top of the first pyramid is converted into silicon oxide by the oxidizing properties of ozone. Then, the silicon oxide is etched away by hydrofluoric acid, resulting in an oxidation-etching cycle. The principle of the first rounding treatment is shown in the following reaction equations: 6Si + 2O3 → 3SiO2; 4HF + SiO2 → SiF4↑ + 2H2O.

[0044] Optionally, the first rounding treatment is carried out at standard atmospheric pressure and a temperature of 10℃ to 25℃, and the treatment time can be adjusted according to process requirements and conditions. The weakly acidic solution is a mixture of HCl, HF, and pure water.

[0045] S14, as shown in Figure 3, involves a second rounding treatment of the first pyramid textured surface 11 using nitric acid and hydrofluoric acid.

[0046] Due to the high surface energy at the base of the pyramid, the solution and air compete for energy during the subsequent wet coating process of the perovskite film. Small air bubbles are prone to remain at the bottom, and the solvent of the perovskite film cannot completely fill the area at the base of the pyramid, resulting in localized pores in this location. This affects charge transport and leads to lower mechanical adhesion between the film and crystalline silicon.

[0047] In this step, the bottom region of the pyramid is etched preferentially by the combined etching of nitric acid and hydrofluoric acid, thereby achieving a second rounding treatment of the bottom of the first pyramid. This eliminates the voids caused by surface tension in the perovskite wet film at the bottom of the pyramid, which is beneficial for the conformal coverage of the subsequent perovskite film.

[0048] Specifically, the silicon substrate 10 treated in step S13 is placed in a mixed solution of nitric acid, hydrofluoric acid, and water for a period of time. The principle of the second rounding treatment is as follows: first, the silicon at the bottom of the pyramid is oxidized to silicon oxide by nitric acid, and then the silicon oxide is removed by hydrofluoric acid to achieve rounding treatment and expose the Si(100) crystal plane of the silicon substrate: Si + 4HNO3 → SiO2 + 4NO2 + 2H2O; 4HF + SiO2 → SiF4↑ + 2H2O.

[0049] S15, a second texturing process is performed on the crystalline silicon substrate to form a second pyramidal textured surface 12; the height of the second pyramidal textured surface 12 is a second height H2, which is less than the first height H1. As shown in Figure 4, Figure 4 shows a schematic diagram after the second texturing process in one embodiment. The second pyramidal textured surface 12 may include a pyramid located at the top of the first pyramidal textured surface 11, or it may include a pyramid located at the bottom of the first pyramidal textured surface 11.

[0050] After the top of the first pyramid textured surface 11 is rounded by the first rounding treatment and the bottom of the first pyramid textured surface 11 is rounded by the second rounding treatment, the Si(100) crystal plane of the crystalline silicon substrate 10 is exposed. This facilitates the formation of a new second pyramid textured surface 12 on the exposed Si(100) crystal plane. In the second texturing process, the formed second pyramid structure is made smaller than the pyramid structure formed by the first texturing process, that is, the second height H2 of the second pyramid textured surface 12 is smaller than the first height H1 of the first pyramid textured surface 11. The first height H1 of the first pyramid textured surface 11 and the second height H2 of the second pyramid textured surface 12 can be adjusted by adjusting the concentration of the texturing agent, the texturing time, etc. This is more conducive to the subsequent formation of perovskite thin films.

[0051] In the above-described method for forming a textured surface on a battery, a first texturing process is first performed on the crystalline silicon substrate 10 to form a first pyramidal textured surface 11. Then, a first rounding process and a second rounding process are performed on the first pyramidal textured surface 11. The first rounding process uses ozone and hydrofluoric acid, preferentially rounding the top of the first pyramidal textured surface. The second rounding process uses nitric acid and hydrofluoric acid, preferentially rounding the bottom of the first pyramidal textured surface. This rounding of both the top and bottom of the first pyramidal textured surface exposes the crystal planes of the crystalline silicon substrate for faster texturing, facilitating the second texturing process. In the second texturing process, the rounded areas form a second pyramidal textured surface 12, further reducing surface energy and facilitating the deposition of perovskite thin films via wet processes, achieving good conformal coverage.

[0052] In this article, "conformal coverage" refers to the ability to maintain the morphology of the substrate surface during film formation.

[0053] In some embodiments, the first height H1 is 4 μm to 6 μm. In some embodiments, the second height H2 is 0.1 μm to 0.4 μm.

[0054] For example, the first height H1 of the first pyramid textured surface 11 refers to the vertical height from the base to the top of the pyramid, and the value of the first height H1 can be 4μm, 4.5μm, 5μm, 5.5μm, or 6μm, etc. The second height H2 of the second pyramid textured surface 12 refers to the vertical height from the base to the top of the pyramid, and the value of the second height H2 can be 0.1μm, 0.2μm, 0.3μm, or 0.4μm.

[0055] In traditional wet processes for preparing perovskite thin films using pyramidal textured surfaces, good conformal coverage cannot be achieved. However, in this embodiment, the combination of a first pyramidal textured surface 11 and a second pyramidal textured surface 12 enables the construction of a small pyramidal structure on a large pyramidal structure, effectively reducing surface energy and improving the conformal coverage of the perovskite thin film.

[0056] In some embodiments, the concentration of ozone introduced during the first rounding process is 10 ppm to 60 ppm.

[0057] In some embodiments, the mass concentration of hydrofluoric acid in the first rounding treatment is 30% to 60%. By using a high concentration of hydrofluoric acid, the rounding effect is improved.

[0058] In some implementations, the total processing time for the first rounding process is 60s to 180s.

[0059] For example, in the first rounding treatment, the concentration of ozone introduced can be, but is not limited to, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, or 60 ppm. The mass concentration of hydrofluoric acid can be, but is not limited to, 30%, 35%, 40%, 45%, 50%, 55%, or 60%. The treatment time can be, but is not limited to, 60 s, 80 s, 100 s, 120 s, 140 s, 160 s, or 180 s.

[0060] In some embodiments, the mass concentration of nitric acid in the second rounding treatment is 2% to 30%.

[0061] In some embodiments, the mass concentration of hydrofluoric acid in the second rounding treatment is 0.5% to 5%. By using a high concentration of hydrofluoric acid, the rounding effect is improved.

[0062] In some implementations, the total processing time for the second rounding process is 60s to 180s.

[0063] For example, in the second rounding treatment, the mass concentration of nitric acid can be, but is not limited to, 2%, 5%, 8%, 10%, 15%, 20%, 25%, or 30%. The concentration of hydrofluoric acid can be, but is not limited to, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%. The treatment time can be, but is not limited to, 60s, 80s, 100s, 120s, 140s, 160s, or 180s. Further, the mass concentration of nitric acid is 2% to 15%.

[0064] In some embodiments, the first rounding process forms an arc with a radius R1 of not less than 0.8 μm at the top of the first pyramid textured surface 11. For example, the arc with a radius R1 of 0.8 μm to 5 μm is formed at the top of the first pyramid textured surface 11. Further, the radius R1 of the top of the first pyramid textured surface 11 can be 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm, etc.

[0065] In some embodiments, during the second rounding process, the base of the first pyramidal textured surface 11 is formed with an arc of radius R2 not less than 0.8 μm. Exemplarily, the base of the first pyramidal textured surface 11 is formed with an arc of radius R2 ranging from 0.8 μm to 5 μm. Further, the radius R2 of the base of the first pyramidal textured surface can be 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm, etc.

[0066] In some embodiments, as shown in FIG5, a method for fabricating a tandem battery is provided, comprising the following steps:

[0067] S21 provides a crystalline silicon substrate 10.

[0068] S22, a first texturing process is performed on the crystalline silicon substrate 10 to form a first pyramid textured surface 11 on the top of the crystalline silicon substrate 10; the height of the first pyramid textured surface 11 is a first height H1.

[0069] S23, the first pyramid velvet surface 11 is subjected to a first rounding treatment using ozone and hydrofluoric acid.

[0070] S24, the first pyramid textured surface 11 is subjected to a second rounding treatment using nitric acid and hydrofluoric acid.

[0071] S25, a second texturing process is performed on the crystalline silicon substrate to form a second pyramid textured surface 12; the height of the second pyramid textured surface 12 is a second height H2, which is less than the first height H1.

[0072] S26, a perovskite thin film solution is formed on a crystalline silicon substrate 10 and dried to obtain a tandem solar cell.

[0073] In step S26, a wet process is used to form a perovskite thin film, that is, a perovskite thin film solution is first deposited on a crystalline silicon substrate, and after drying, a conformal perovskite thin film is formed to obtain a tandem solar cell.

[0074] Optionally, in step S26, before forming the perovskite thin film on the crystalline silicon substrate 10, a transparent conductive layer and a first carrier transport layer are also formed on the crystalline silicon substrate 10; a second carrier transport layer and a top electrode are also formed on the perovskite thin film; the first carrier transport layer is an electron transport layer and the second carrier transport layer is a hole transport layer, or the first carrier transport layer is a hole transport layer and the second carrier transport layer is a transport layer electron.

[0075] For example, the perovskite thin film solution can be a solution of FACsPbIBrCl, FAMACsPbIBrCl, FACsDMAPbIBrCl, CsDMAPbIBrCl, FACsPbIBr, FAMACsPbSnIbIBr, FACsDMAPbIBr, or CsDMAPbIBr.

[0076] The relevant content of each step in this embodiment can be referred to the relevant content of any embodiment, and will not be repeated here.

[0077] In some embodiments, this application also provides a stacked battery, the stacked battery comprising: a crystalline silicon substrate 10, the upper surface of the crystalline silicon substrate 10 defining a first pyramidal textured surface 11, the top and bottom of the first pyramidal textured surface 11 being at least partially arcuate structures, a second pyramidal textured surface 12 defining the arcuate structures, the second height H2 of the second pyramidal textured surface 12 being less than the first height H1 of the first pyramidal textured surface 11; and a perovskite thin film conformally covering the upper surface of the crystalline silicon substrate 10.

[0078] Optionally, a transparent conductive layer and a first carrier transport layer are also formed on the crystalline silicon substrate 10; a second carrier transport layer and a top electrode are also formed on the perovskite thin film; the first carrier transport layer is an electron transport layer and the second carrier transport layer is a hole transport layer, or the first carrier transport layer is a hole transport layer and the second carrier transport layer is a transport layer electron.

[0079] In some embodiments, the first height H1 of the first pyramidal textured surface 11 is 4 μm to 6 μm; and / or, the second height H2 of the second pyramidal textured surface 12 is 0.1 μm to 0.4 μm. Exemplarily, the first height H1 of the first pyramidal textured surface 11 refers to the vertical height from the base to the top of the pyramid, and the value of the first height H1 can be 4 μm, 4.5 μm, 5 μm, 5.5 μm, or 6 μm, etc. The second height H2 of the second pyramidal textured surface 12 refers to the vertical height from the base to the top of the pyramid, and the value of the second height H2 can be 0.1 μm, 0.2 μm, 0.3 μm, or 0.4 μm.

[0080] The relevant content of each unit / part in this embodiment can be referred to the relevant content in any other embodiment, and will not be repeated here.

[0081] The following are specific examples.

[0082] Example 1, a method for forming a textured surface on a battery, comprising:

[0083] S11 provides a crystalline silicon substrate.

[0084] S12, a commercial texturing agent (Xi'an Lanqiao New Energy Technology Co., Ltd., LQ6SB01) is used to perform a first texturing treatment on the crystalline silicon substrate to form a first pyramid textured surface on the top of the crystalline silicon substrate; the first height H1 of the first pyramid textured surface is 5μm.

[0085] S13, the first pyramid textured surface undergoes a first rounding treatment using ozone and hydrofluoric acid. Specifically, ozone is introduced into a weakly acidic solution, and after stabilization, the crystalline silicon substrate 10 treated in step S12 is placed in the solution for a period of time. This forms an arc with a radius R1 of 1.5 μm at the top of the first pyramid textured surface. The ozone concentration is 40 ppm, the hydrofluoric acid mass concentration is 45%, and the total treatment time is 120 s.

[0086] S14, the first pyramid textured surface undergoes a second rounding treatment using nitric acid and hydrofluoric acid. The silicon substrate 10 treated in step S13 is immersed in a mixed solution of nitric acid, hydrofluoric acid, and water for a period of time. This forms an arc with a radius R2 of 1.5 μm at the base of the first pyramid textured surface. The mass concentration of nitric acid is 15%, the mass concentration of hydrofluoric acid is 2%, and the total treatment time is 120 s.

[0087] S15, a second texturing process is performed on the crystalline silicon substrate using a commercial texturing agent (Xi'an Lanqiao New Energy Technology Co., Ltd., LQ6S) to form a second pyramid textured surface, the second height H2 of which is 0.2μm.

[0088] The fabrication method of the tandem solar cell is as follows: a perovskite thin film solution is deposited on the textured surface of the prepared solar cell, and after drying, a perovskite thin film is formed on crystalline silicon to obtain the tandem solar cell. The perovskite thin film solution is FA. 0.95 Cs 0.05 PbI3 solution.

[0089] Example 2

[0090] The preparation method of Example 2 is basically the same as that of Example 1, except that in step S12, the first height H1 of the first pyramid textured surface is 4 μm.

[0091] Example 3

[0092] The preparation method of Example 3 is basically the same as that of Example 1, except that in step S12, the first height H1 of the first pyramid textured surface is 6 μm.

[0093] Example 4

[0094] The preparation method of Example 4 is basically the same as that of Example 1, except that in step S13, the ozone concentration is 10 ppm and the mass concentration of hydrofluoric acid is 60%, thereby forming an arc with a radius R1 of 0.8 μm at the top of the first pyramid textured surface.

[0095] Example 5

[0096] The preparation method of Example 5 is basically the same as that of Example 1, except that in step S13, the ozone concentration is 60 ppm and the mass concentration of hydrofluoric acid is 30%, thereby forming an arc with a radius R1 of 2 μm at the top of the first pyramid textured surface.

[0097] Example 6

[0098] The preparation method of Example 6 is basically the same as that of Example 1, except that in step S14, the mass concentration of nitric acid is 2% and the mass concentration of hydrofluoric acid is 5%, thereby forming an arc with a radius R2 of 0.8 μm at the bottom of the first pyramid textured surface.

[0099] Example 7

[0100] The preparation method of Example 7 is basically the same as that of Example 1, except that in step S14, the mass concentration of nitric acid is 30% and the mass concentration of hydrofluoric acid is 0.5%, thereby forming an arc with a radius R2 of 1μm at the bottom of the first pyramid textured surface.

[0101] Example 8

[0102] The preparation method of Example 8 is basically the same as that of Example 1, except that in step S15, the first height H1 of the second pyramid textured surface is 0.1 μm.

[0103] Example 9

[0104] The preparation method of Example 9 is basically the same as that of Example 1, except that in step S15, the first height H1 of the second pyramid textured surface is 0.4 μm.

[0105] Comparative Example 1

[0106] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that steps S12 to S15 are not performed.

[0107] The preparation methods and process parameters for Examples 1-9 and Comparative Example 1 are listed in Table 1 below:

[0108] Table 1

[0109] The battery textured surfaces prepared in Examples 1-9 and Comparative Example 1 were subjected to performance tests, and the test results are shown in Table 2 below.

[0110] The test conditions or test standards for each performance test item are as follows.

[0111] The water droplet angle is the contact angle of a perovskite solution on a silicon wafer after texturing and cleaning. The test conditions for the water droplet angle are: the perovskite precursor solution is dropped onto the surface of the silicon wafer, and due to the surface tension of the liquid, an angle is formed between the liquid and the solid. The test is conducted at the solid-liquid-gas three-phase interface point, and the angle formed by the two tangents of the gas-liquid interface and the solid-liquid interface trapping the liquid phase is the water droplet angle.

[0112] The reflectivity test conditions were as follows: the tandem solar cell sample was held in an 8° angled porous integrating sphere and illuminated by an incident light beam. The light was reflected multiple times by the inner wall of the sphere until it was detected by the photodetector. The 8° angled porous integrating sphere is a sphere with a special angle and porous structure. The photodetector was positioned at 8°, and the incident light beam entered the integrating sphere through the porous structure. The light was reflected multiple times by the inner wall of the sphere, allowing the scattered light to uniformly illuminate the tandem solar cell sample from various angles until it was detected by the photodetector. The reflectivity of the tandem solar cell sample was measured in the 300nm–1200nm wavelength range, and the average value from 500nm to 1000nm was taken.

[0113] EFF refers to the conversion efficiency of a solar cell made from a texturized and cleaned silicon wafer. The EFF test conditions are as follows: an artificial light source simulating the sun is prepared, with light intensity and spectrum calibrated to AM1.5G; the temperature of the tandem solar cell sample is controlled within the range of 25±2℃; and the solar cell's photoluminescence (IV) curve is tracked and obtained by changing the variable resistance at both ends of the cell and recording the voltage and current at the cell terminals. Where V... OC (Open-circuit voltage) is the voltage at which zero current is applied, I SC (Short-circuit current) is the current at zero voltage, EFF is the maximum value of the product of current and voltage, i.e., the maximum output power, and FF is the ratio of the maximum output power to the product of the short-circuit current and the open-circuit voltage.

[0114] Table 2

[0115] As shown in Table 2 above, compared with Comparative Example 1, Examples 1-9 have higher FF and EFF without a significant decrease in reflectivity. This indicates that the perovskite film layer of Examples 1-9 has better coverage on the silicon wafer pyramid surface, proving that the textured surface formation method provided in this application can effectively improve the yield of tandem solar cell fabrication, thereby bringing about optimization in terms of conversion efficiency and electrical performance.

[0116] 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.

[0117] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for forming a textured surface on a battery, comprising the following steps: Provide crystalline silicon substrates; The crystalline silicon substrate is subjected to a first texturing process to form a first pyramidal texturing surface on the top of the crystalline silicon substrate; the height of the first pyramidal texturing surface is a first height. The first pyramid textured surface is subjected to a first rounding treatment using ozone and hydrofluoric acid. The first pyramid textured surface is subjected to a second rounding treatment using nitric acid and hydrofluoric acid; The crystalline silicon substrate is subjected to a second texturing process to form a second pyramidal textured surface; the height of the second pyramidal textured surface is a second height, which is less than the first height.

2. The method according to claim 1, wherein, The first height is 4μm to 6μm.

3. The method according to any one of claims 1 to 2, wherein, The second height is 0.1 μm to 0.4 μm.

4. The method according to any one of claims 1 to 3, wherein, In the first rounding treatment, the concentration of ozone introduced is 10ppm to 60ppm.

5. The method according to any one of claims 1 to 4, wherein, In the first rounding treatment, the mass concentration of hydrofluoric acid is 30% to 60%.

6. The method according to any one of claims 1 to 5, wherein, In the first rounding process, the total processing time is 60s to 180s.

7. The method according to any one of claims 1 to 6, wherein, In the second rounding treatment, the mass concentration of nitric acid is 2% to 30%.

8. The method according to claim 7, wherein, In the second rounding treatment, the mass concentration of the nitric acid is 2% to 15%.

9. The method according to any one of claims 1 to 8, wherein, In the second rounding treatment, the mass concentration of hydrofluoric acid is 0.5% to 5%.

10. The method according to any one of claims 1 to 9, wherein, In the second rounding process, the total processing time is 60s to 180s.

11. The method according to any one of claims 1 to 10, wherein, In the first rounding process, the top of the first pyramid textured surface is formed with an arc with a radius of not less than 0.8 μm.

12. The method according to any one of claims 1 to 11, wherein, In the second rounding process, the base of the first pyramid textured surface is formed with an arc having a radius of not less than 0.8 μm.

13. A method for preparing a tandem solar cell, comprising the following steps: Provide crystalline silicon substrates; The crystalline silicon substrate is subjected to a first texturing process to form a first pyramidal texturing surface on the top of the crystalline silicon substrate; the height of the first pyramidal texturing surface is a first height. The first pyramid textured surface is subjected to a first rounding treatment using ozone and hydrofluoric acid. The first pyramid textured surface is subjected to a second rounding treatment using nitric acid and hydrofluoric acid; The crystalline silicon substrate is subjected to a second texturing process to form a second pyramidal textured surface; the height of the second pyramidal textured surface is a second height, which is less than the first height. A perovskite thin film solution is formed on the crystalline silicon substrate and dried to obtain a tandem battery.

14. A stacked battery, wherein, The stacked battery includes: A crystalline silicon substrate, wherein the upper surface of the crystalline silicon substrate defines a first pyramidal textured surface, the top and bottom of the first pyramidal textured surface being at least partially arc-shaped structures, and a second pyramidal textured surface is defined on the arc-shaped structures, wherein the second height of the second pyramidal textured surface is less than the first height of the first pyramidal textured surface; A perovskite thin film, conformally covering the upper surface of the crystalline silicon substrate.

15. The stacked battery according to claim 14, wherein, At least one of the following conditions must be met: (1) The first height of the first pyramid velvet surface is 4μm to 6μm; (2) The second height of the second pyramid textured surface is 0.1μm to 0.4μm.

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