Solar cell and preparation method thereof
By forming a uniform microstructure textured surface on the silicon substrate through a two-step texturing method, the problems of textured surface uniformity and unstable reflectivity are solved, achieving high-efficiency photoelectric conversion and excellent appearance, thus enhancing the market competitiveness of solar cells.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-04-07
AI Technical Summary
The one-step texturing process results in poor uniformity of the texturing surface and unstable reflectivity control, which fails to meet market requirements for the appearance of black components and affects photoelectric conversion efficiency and product appearance.
A two-step texturing method is adopted. First, a high-concentration texturing solution is used to treat the cells for a short time to form high-density microstructure nucleation sites. Then, a low-concentration texturing solution is used to extend the treatment time to promote the growth of nucleation sites, thereby controlling the state of the solution and the nucleation process.
It improves the quality and consistency of the velvet surface, reduces reflectivity, optimizes the uniformity and color of the antireflective film, and enhances photoelectric conversion efficiency and product market competitiveness.
Smart Images
Figure CN121815801A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of photovoltaic technology, and more specifically, to a solar cell and a method for its fabrication. Background Technology
[0002] In the manufacturing process of crystalline silicon solar cells, the formation of a textured surface is one of the key steps to improve photoelectric conversion efficiency. Traditional texturing, also known as one-step texturing, typically involves immersing the silicon wafer in a texturing solution containing sodium hydroxide or potassium hydroxide, where chemical etching forms a pyramidal texture on the wafer surface. This method utilizes the anisotropic etching rates of different silicon crystal planes in an alkaline solution, primarily guiding the formation of a pyramidal texture on the (111) crystal plane through the etching of the (100) plane. However, one-step texturing has significant drawbacks, which become more pronounced as the solution lifetime increases.
[0003] With repeated use of the texturing solution, silicates, a byproduct generated during the reaction, gradually accumulate, leading to increased solution viscosity, decreased fluidity of the solution on the silicon wafer surface, reduced exchange rate, and hindered bubble escape. These factors combined make controlling the texturing process difficult, reducing uniformity, and causing inconsistencies in texture size and distribution. This affects the reflectivity of the textured surface, reduces solar absorption efficiency, and consequently impacts the photoelectric conversion efficiency of the solar cell. Furthermore, the instability of the textured surface quality further affects the uniformity and color of the subsequently deposited antireflective film, resulting in a final product appearance that does not meet current market requirements for "black modules" (i.e., modules with a deep, uniform black color).
[0004] Therefore, in order to solve the technical problems of poor uniformity of the texturing surface, unstable reflectivity control, and inability to meet the current market requirements for the color of black module films in the one-step texturing process, a new texturing method is urgently needed to improve the uniformity and consistency of the texturing surface. Summary of the Invention
[0005] This application provides a solar cell and its preparation method to solve the problems of poor uniformity of the texturing surface and unstable reflectivity control in the related technology.
[0006] According to one aspect of this application, a method for preparing a solar cell is provided, comprising the following steps:
[0007] A silicon substrate is provided, and a first step texturing and a second step texturing are performed sequentially on the silicon substrate to form a textured surface on at least one side surface of the silicon substrate. The processing time of the first step texturing is less than the processing time of the second step texturing, and the concentration of the texturing solution used in the first step texturing is greater than the concentration of the texturing solution used in the second step texturing.
[0008] Optionally, the texturing solution is a mixture comprising a first alkaline solution and a nucleating additive, wherein the concentration of the first alkaline solution is 1-5 wt%.
[0009] Optionally, the processing time for the first step of flocking is 20-90 seconds.
[0010] Optionally, the texturing solution is a mixture comprising a second alkaline solution and a nucleating additive, wherein the concentration of the second alkaline solution is 0.5-2.5 wt%.
[0011] Optionally, the processing time for the second step of texturing is 5-15 minutes.
[0012] Optionally, the temperature of the first step of the flocking process is 70-85℃, and the temperature of the second step of the flocking process is 70-80℃.
[0013] According to another aspect of this application, a solar cell is provided, which is prepared by the aforementioned preparation method. The solar cell includes: a silicon substrate, at least one surface of the silicon substrate having a textured surface, the textured surface including a plurality of microstructures, the bottom surface of the microstructures being polygonal, and the diagonal length of the bottom surface being less than 1.5 μm, and the height of the microstructures being less than 1.1 μm.
[0014] Optionally, the diagonal length of the bottom surface of the microstructure is less than 0.1-1 μm, and the height of the microstructure is less than 0.1-1 μm.
[0015] Optionally, the variance of the diagonal of the bottom surface of the microstructure is less than 0.1.
[0016] Optionally, the surface reflectivity of the silicon substrate having the textured surface is less than 10%.
[0017] Optionally, the solar cell further includes an antireflective coating located on the side of the silicon substrate having the textured surface.
[0018] Optionally, the thickness uniformity of the antireflective film is less than 10%.
[0019] Optionally, the refractive index uniformity of the antireflective film is less than 1.2%.
[0020] This application employs a two-step texturing method to form a textured surface on at least one side of a silicon substrate. The first texturing step has a shorter processing time than the second step, and the concentration of the texturing solution used in the first step is higher than that used in the second step. First, the silicon substrate undergoes a pre-etching / nucleation step using a high-concentration but short-time texturing solution to rapidly form long-lived, high-density microstructure nucleation sites on the substrate surface. Due to the short processing time, the total amount of silicon dissolved in the substrate at this stage is limited, thus avoiding rapid accumulation of sodium silicate in the solution and maintaining its optimal condition. Next, in the main etching / growth step, the silicon substrate is immediately immersed in a lower-concentration texturing solution, thereby promoting nucleation site growth. Although the processing time is much longer than the pre-nucleation step, and the amount of silicon dissolved in the substrate is correspondingly increased, the solution's sensitivity to additive failure and byproducts is significantly reduced because a uniform nucleation base has been successfully established in the pre-nucleation stage. This is because the uniform and dense nucleation sites themselves can guide the chemical reaction in the solution towards uniform growth. Even if some properties of the solution change over time, the negative impact on the texturing growth is relatively small. By controlling the nucleation and growth processes in stages, the quality of the texturing surface is improved, reflectivity is reduced and stabilized, and the color of the subsequently deposited antireflective film is deeper and more uniform, meeting the appearance requirements of black modules. This method not only improves photoelectric conversion efficiency but also optimizes the battery appearance, enhancing the product's market competitiveness. By controlling the concentration and processing time of different texturing solutions in the two-step texturing process, the microstructure size of the texturing surface becomes more uniform, the distribution is denser, and the coverage is more complete, thereby enhancing the absorption of incident light and reducing surface reflectivity. In addition, the staged texturing process improves the consistency of the texturing surface throughout the entire solution cycle, reduces process sensitivity, and makes the production process more stable and controllable. Attached Figure Description
[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:
[0022] Figure 1 This is a schematic flowchart of a method for preparing a solar cell according to an embodiment of this application;
[0023] Figure 2 is a SEM image of the texturing surface according to Example 1 and Comparative Example 1;
[0024] Figure 3 is an appearance diagram of the antireflective film deposited according to Example 1 and Comparative Example 1. Detailed Implementation
[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.
[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.
[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0028] As described in the background section, the viscosity of the texturing solution increases during its usage cycle due to the accumulation of byproducts. This affects the fluidity and reaction efficiency of the solution, resulting in uneven texturing and reduced light absorption. Secondly, the random nucleation process in one-step texturing leads to inconsistencies in the size and distribution of the texturing surface structure, and the instability of the texturing surface reflectivity directly affects the improvement of photoelectric conversion efficiency. Thirdly, the uneven texturing quality will be reflected in inconsistent film color during subsequent antireflective film deposition, failing to meet market requirements for deep black and uniform appearance components. To solve the above technical problems, embodiments of this application provide a solar cell and its fabrication method.
[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
[0030] According to one embodiment of this application, a method for preparing a solar cell is provided, comprising the following steps:
[0031] A silicon substrate is provided, and a first step texturing and a second step texturing are performed sequentially on the silicon substrate to form a textured surface on at least one side of the silicon substrate. The processing time of the first step texturing is less than the processing time of the second step texturing, and the concentration of the texturing solution used in the first step texturing is greater than the concentration of the texturing solution used in the second step texturing.
[0032] The embodiments of this application achieve high-quality growth of textured structures. Specifically, the silicon substrate first undergoes a pre-etching / nucleation step using a high-concentration but short-time texturing solution to rapidly form long-lived, high-density microstructure nucleation sites on the silicon substrate surface. Due to the short processing time, the total amount of silicon dissolved in the silicon substrate at this stage is limited, thus avoiding the rapid accumulation of sodium silicate in the solution and maintaining the good condition of the solution. Next, in the main etching / growth step, the silicon substrate is immediately immersed in a lower-concentration texturing solution, thereby promoting the growth of nucleation sites. Although the processing time is much longer than the pre-nucleation step, and the amount of silicon dissolved in the silicon substrate is correspondingly increased, the solution's sensitivity to additive failure and byproducts is significantly reduced because a uniform nucleation base has been successfully established in the pre-nucleation stage. This is because the uniform and dense nucleation sites themselves can guide the chemical reactions in the solution towards uniform growth, and even if some properties of the solution change over time, the negative impact on textured growth is relatively small. By controlling the nucleation and growth processes in stages, the quality of the texturing surface was improved, reflectivity was reduced and stabilized, and the color of the subsequently deposited antireflective film was made deeper and more uniform, meeting the appearance requirements of black modules. This method not only improves photoelectric conversion efficiency but also optimizes the battery appearance, enhancing the product's market competitiveness. By controlling the concentration and processing time of different texturing solutions in the two-step texturing process, the microstructure size of the texturized surface is made more uniform, the distribution is denser, and the coverage is more complete, thereby enhancing the absorption of incident light and reducing surface reflectivity. In addition, the staged texturing process improves the consistency of the texturized surface throughout the entire chemical solution cycle, reduces process sensitivity, and makes the production process more stable and controllable.
[0033] In some alternative embodiments, the texturing solution is a mixture comprising a first alkaline solution and a nucleating additive, wherein the concentration of the first alkaline solution is 1-5 wt%.
[0034] In the above optional embodiments, the texturing solution consists of a first alkaline solution and a nucleation additive. The concentration of the first alkaline solution is set between 1 and 5 wt%. This concentration range ensures the rapid formation of high-density, uniformly distributed microstructure nucleation centers on the silicon wafer surface, laying a solid foundation for subsequent texturing growth. The introduction of the nucleation additive further enhances the uniformity and efficiency of nucleation, enabling ideal nucleation results even with short processing times. The high-concentration alkaline solution and the nucleation additive work synergistically to accelerate the nucleation process, ensuring high uniformity and density of nucleation points, avoiding randomness in texturing growth, and laying the foundation for subsequent growth steps. This embodiment optimizes the reaction rate and nucleation density by controlling the concentration of the alkaline solution, avoiding the problems of uneven texturing growth and increased reflectivity caused by high-concentration solutions during long-term reactions.
[0035] In some alternative embodiments, the texturing solution is a mixture comprising a second alkaline solution and a nucleating additive, wherein the concentration of the second alkaline solution is 0.5-2.5 wt%.
[0036] In the above-mentioned optional embodiments, by controlling the concentration range (0.5-2.5 wt%) and composition of the texturing solution, the growth rate and quality of nucleation points can be optimized during the texturing stage. This not only promotes the uniform expansion of microstructures but also effectively avoids the negative impact of byproduct accumulation in the solution on the growth process, thereby improving the overall uniformity and integrity of the texturing surface. Furthermore, by maintaining the solution in optimal working condition, the service life of the solution is extended, production costs are reduced, and production efficiency is improved.
[0037] In some alternative implementations, the first step of texturing takes 20-90 seconds.
[0038] In the above optional embodiments, the first texturing step is limited to 20 to 90 seconds. Its purpose is to rapidly establish a high density of microstructure nucleation sites on the silicon substrate surface, promoting a rapid and uniform nucleation process. These nucleation sites provide an ideal starting point for subsequent texturing growth, ensuring the basic conditions for subsequent texturing. Because the first texturing step uses a high-concentration solution, texturing seeds can be generated efficiently in a short time, thereby reducing the accumulation rate of silicate byproducts in the solution and avoiding the impact of increased solution viscosity on the nucleation site distribution.
[0039] In some alternative implementations, the first step of texturing takes 5-15 minutes.
[0040] In the above optional embodiments, the second step of texturing has a longer processing time, allowing the nucleation centers to grow fully and form a microstructured texturing surface with complete coverage and uniform size. Thus, by controlling the processing time of the second step of texturing, not only is the quality of the texturing surface optimized, but the utilization rate of the drug solution is also improved, and the impact of sodium silicate accumulation on the viscosity and reaction rate of the drug solution during the texturing process is reduced.
[0041] In some alternative implementations, the temperature of the first step of the texturing process is 70-85°C, and the temperature of the second step of the texturing process is 70-80°C.
[0042] In the above optional embodiments, by specifying the temperature range of the first and second texturing steps, i.e., the temperature of the first texturing step is set between 70-85℃, and the temperature of the second texturing step is adjusted to a slightly lower range of 70-80℃, more precise temperature control of the texturing growth process is achieved. This promotes the rapid formation and stabilization of nucleation points on the silicon wafer surface, while ensuring the uniform expansion of the texturing structure in subsequent growth stages, reducing texturing defects caused by temperature fluctuations, and thus improving the controllability and quality of the entire texturing process.
[0043] According to the embodiments of this application, such as Figure 1 As shown, the fabrication method of a solar cell may include the following process flow:
[0044] S1, Silicon Wafer Pre-treatment:
[0045] Cleaning silicon wafers: Remove impurities and residues from the surface of the silicon wafers in preparation for texturing.
[0046] S2, Pre-corrosion / nucleation:
[0047] The cleaned silicon wafers are immersed in a high-concentration nucleation solution, which is a mixture of an alkaline solution (such as NaOH) and a nucleation additive.
[0048] The alkaline concentration of the nucleation drug solution ranges from 1 to 5 wt%, and the temperature is controlled at 70 to 85℃.
[0049] The reaction time of silicon wafers in nucleation solutions is short, typically 20-90 seconds;
[0050] The goal is to rapidly form high-density, uniformly distributed pyramid-shaped core centers on the surface of a silicon wafer.
[0051] S3, Main corrosion / growth:
[0052] Immediately transfer the pre-etched silicon wafer into a low-concentration growth solution, which is a mixture of alkaline solution and additives.
[0053] The alkaline concentration of the growth agent solution ranges from 0.5 to 2.5 wt%, and the temperature is controlled at 70-80℃.
[0054] The reaction time of silicon wafers in the growth solution is relatively long, usually 5-15 minutes;
[0055] The goal is to allow the nucleation center to grow into a complete and uniform pyramidal textured structure.
[0056] S4, Post-wash:
[0057] Remove the silicon wafer and sequentially pass it through dilute hydrochloric acid neutralization, deionized water rinsing, and HF acid rinsing.
[0058] After cleaning, the silicon wafer is dried to remove chemical residues from the surface and ensure a clean surface in preparation for subsequent coating.
[0059] S5, Deposited passivation film:
[0060] A silicon wafer is placed in an ALD (atomic layer deposition) cavity and inserted into a boat to prepare 0.5 nm ultrathin silicon oxide and 5 nm aluminum oxide.
[0061] S6, Deposited antireflective coating:
[0062] A silicon nitride / silicon oxynitride / silicon oxide composite antireflective film with a total thickness of approximately 80 nm was deposited on the front side of a silicon wafer using a tubular PECVD (plasma-enhanced chemical vapor deposition) equipment.
[0063] The aim is to further reduce reflectivity, improve light absorption efficiency, and optimize the battery appearance.
[0064] S7, Backsheet preparation and sintering:
[0065] An ultrathin silicon oxide / alumina / silicon nitride / silicon oxide stack was prepared, and sintered and tested according to conventional processes.
[0066] In this embodiment, the entire texturing process aims to improve the uniformity and quality of the texturing surface, reduce reflectivity, and optimize the appearance of the antireflective film by controlling the chemical parameters and processing time of the two texturing tanks, thereby improving the photoelectric conversion efficiency and market competitiveness of the battery.
[0067] According to one embodiment of this application, a solar cell is provided, which is prepared by the preparation method in the above embodiment. The solar cell includes: a silicon substrate, at least one side surface of the silicon substrate has a textured surface, the textured surface includes a plurality of microstructures, the bottom surface of the microstructures is polygonal, and the diagonal length of the bottom surface is less than 1.5 μm, and the height of the microstructures is less than 1.1 μm.
[0068] This application provides a solar cell fabricated using a stepwise texturing method. During the texturing process, a textured surface is formed on at least one side of a silicon substrate. This textured surface contains multiple microstructures, each with a polygonal base, a diagonal length of less than 1.5 μm, and a height of less than 1.1 μm. The key to this texturing method lies in dividing the process into two independent steps: pre-etching (nucleation) and main etching (growth). First, a high-concentration texturing solution is used to form a large number of uniformly distributed microstructure nucleation points in a short time. Subsequently, in a lower-concentration texturing solution, these nucleation points gradually grow into smaller and lower-height microstructures, effectively improving the textured surface quality and the uniformity of the black module film color. Although the processing time is longer, the uniform distribution of nucleation points and the more controllable growth process result in a uniformly sized, fully covered microstructure textured surface, significantly reducing the reflectivity of the silicon wafer surface, increasing light absorption, and thus promoting higher photoelectric conversion efficiency. Therefore, in the solar cells of this application embodiment, the textured microstructure is smaller and more uniformly distributed, which improves the light capture efficiency and reduces the reflectivity. The silicon substrate surface obtained after texturing is conducive to the subsequent deposition of antireflective film, and the resulting film layer is darker and more uniform in color, meeting the appearance requirements of black modules. The solar cell has higher photoelectric conversion efficiency, which meets market demand and enhances the market competitiveness of the product.
[0069] In some alternative implementations, the diagonal length of the bottom surface of the microstructure is less than 0.1-1 μm, and the height of the microstructure is less than 0.1-1 μm.
[0070] In the aforementioned optional embodiments, the diagonal length of the bottom surface of the microstructure is controlled within the range of 0.1-1 μm, and the height of the microstructure is also maintained within the range of 0.1-1 μm, thereby refining the textured surface structure. Specifically, by precisely controlling the size of the pyramid-shaped microstructure, a finer and more uniform texture can be constructed on the silicon wafer surface. This texture not only increases the interaction area with light, effectively reducing light reflection, but also significantly improves the light capture efficiency, thereby increasing the photoelectric conversion efficiency of the solar cell. Furthermore, the uniformity of the microstructure size facilitates the uniform deposition of subsequent anti-reflection coatings, optimizes the optical performance of the coatings, and makes the front surface of the solar cell exhibit a deep and consistent color, which better meets the high-standard appearance requirements of black modules.
[0071] In some alternative implementations, the variance of the diagonal of the microstructure bottom surface is less than 0.1.
[0072] In the above optional embodiments, the diagonal variance of the microstructure bottom surface is controlled within a range of less than 0.1. By adjusting the size of the textured microstructure, the geometric consistency of the textured structure is ensured. Low variance means that the variation of the diagonal length of the pyramid bottom surface is extremely small, which macroscopically manifests as the consistency of textured height and the uniform distribution of textured surface. This not only reduces optical reflection loss, but also promotes the uniform deposition of subsequent silicon nitride antireflection film, forming a high-quality battery surface with small color difference and deep black color.
[0073] In some alternative implementations, the surface reflectivity of the textured silicon substrate is less than 10%.
[0074] Specifically, in this embodiment, the control of the nucleation and growth process on the silicon wafer surface through texturing ensures a more consistent microscopic size of the textured structure, thereby effectively reducing light reflection on the silicon substrate surface. Specifically, a short treatment with a high-concentration solution is used to form dense nucleation points, followed by a long growth period in a lower-concentration solution. This results in a highly uniform pyramidal textured surface in both size and distribution, thereby reducing and stabilizing surface reflectivity. Simultaneously, due to the reduced reflectivity, the subsequently deposited anti-reflective film can exhibit a deeper and more uniform color, meeting the high-end market's requirement for a deep and consistent black color for black components, thus enhancing the product's market competitiveness.
[0075] In this embodiment, the solar cell may further include an antireflective coating located on the textured side of the silicon substrate. The texturing strategy employed in this application not only significantly reduces the reflectivity of the textured surface and improves the absorption efficiency of sunlight, but also optimizes the deposition conditions of the antireflective coating. This results in more stable optical properties and a more uniform and deeper color when the film is deposited on a uniformly textured surface with low reflectivity. Consequently, the solar cell not only achieves improved photoelectric conversion efficiency but also better meets the high standards required for black modules in terms of front-side appearance.
[0076] In some alternative implementations, the thickness uniformity of the antireflective film is less than 10%.
[0077] Specifically, the texturing process in this application significantly improves the uniformity of the textured surface structure of the silicon wafer through independent pre-nucleation and main growth steps. The pre-nucleation step forms high-density and uniformly distributed pyramidal nuclei on the silicon wafer surface, providing an ideal starting point for subsequent textured growth. The main growth step allows the nuclei to develop into a consistent microstructure under milder conditions, reducing uneven textured growth caused by changes in solution viscosity. Since the uniformity of the textured structure directly affects the deposition effect of the antireflective coating, the silicon wafer with step-by-step texturing exhibits more consistent film growth during antireflective coating deposition, thus achieving the goal of antireflective coating thickness uniformity of less than 10%. This optimization not only improves the quality of the antireflective coating but also enhances the optical performance of the film by reducing the refractive index difference between film layers, reducing reflectivity, increasing sunlight absorption, and ultimately improving the photoelectric conversion efficiency of the solar cell. Furthermore, the uniformity and dark appearance of the antireflective coating meet the current market's aesthetic demand for "black modules," enhancing the product's market competitiveness.
[0078] In some alternative implementations, the refractive index uniformity of the antireflective coating is less than 1.2%.
[0079] In the above optional embodiments, the high consistency of the refractive index of the film layer can be achieved by controlling the chemical composition and environmental conditions during the antireflection film deposition process. Since the uniformity of the refractive index of the solar cell directly affects the transmission and reflection behavior of light on the cell surface, the overall photoelectric conversion efficiency of the cell is optimized by limiting the above refractive index uniformity.
[0080] The following will further illustrate a solar cell and its fabrication method provided in this application with reference to specific embodiments and comparative examples.
[0081] Example 1
[0082] This embodiment uses a step-by-step flocking process, which includes the following steps:
[0083] Pre-nucleation: The polished and cleaned silicon wafer is immersed in a first texturing solution of NaOH with a concentration of 2.0 wt% and a temperature of 78°C, and reacted for 60 seconds.
[0084] Texture growth: Immediately transfer the silicon wafer into a second texturing solution of NaOH with a concentration of 1.5 wt% and a temperature of 80°C, and react for 480 seconds.
[0085] Post-cleaning: Remove the silicon wafer and pass it through a series of steps, including neutralization with dilute hydrochloric acid, rinsing with deionized water, rinsing with HF acid, and finally drying.
[0086] A silicon wafer substrate was inserted into a boat and placed in an ALD cavity to prepare 0.5 nm ultrathin silicon oxide and 5 nm aluminum oxide.
[0087] Deposition of antireflective coating: Using a tubular PECVD equipment, a silicon nitride / silicon oxynitride / silicon oxide composite antireflective coating with a total thickness of approximately 80 nm is deposited on the front side of the silicon wafer using conventional methods.
[0088] Prepare an ultrathin backsheet of silicon oxide / alumina / silicon nitride / silicon oxide, then sinter and test.
[0089] Comparative Example 1
[0090] This comparative example uses a one-step flocking method. The flocking process includes the following steps:
[0091] The polished and cleaned silicon wafers were immersed in a first texturing solution of NaOH with a concentration of 2.1 wt% and a temperature of 80°C, and reacted for 540 seconds.
[0092] Deposition of antireflective coating: Using a tubular PECVD equipment, a silicon nitride / silicon oxynitride / silicon oxide composite antireflective coating with a total thickness of approximately 80 nm is deposited on the front side of the silicon wafer using conventional methods.
[0093] Prepare an ultrathin backsheet of silicon oxide / alumina / silicon nitride / silicon oxide, then sinter and test.
[0094] The SEM images of the fabricated surfaces in Example 1 and Comparative Example 1 are shown in Figure 2. The fabricated surface in Comparative Example 1 is shown in Figure 2(a), and the fabricated surface in Example 1 is shown in Figure 2(b).
[0095] After depositing antireflective films on the texturing surfaces in Example 1 and Comparative Example 1, the film color appearances were collected as shown in Figure 3. The film color appearance in Comparative Example 1 is shown in Figure 3(a), and the film color appearance in Example 1 is shown in Figure 3(b).
[0096] The surface parameters of silicon wafers under the two texturing methods in Example 1 and Comparative Example 1 were tested, and the test results are shown in Table 1.
[0097] Table 1
[0098]
[0099] The film thickness / refractive index after coating was tested under the two texturing methods in Example 1 and Comparative Example 1. The test results are shown in Table 2.
[0100] Table 2
[0101]
[0102] The PL fitting efficiency of the solar cells prepared under the two texturing methods in Example 1 and Comparative Example 1 is compared, as shown in Table 3.
[0103] Table 3
[0104]
[0105] The above test results show that:
[0106] 1) The embodiments of this application adopt a step-by-step flocking process, which results in better flock uniformity, higher flock yield, and lower flock reflectivity;
[0107] 2) The solar cells prepared using the step-by-step texturing process in this application have better photoelectric conversion efficiency;
[0108] 3) The solar cells prepared by the step texturing process in this application have a more uniform and deeper color on the front side, which better meets the requirements of the black module film color.
[0109] 4) The surface uniformity of this application embodiment is better throughout the entire drug solution cycle.
[0110] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.
[0111] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.
Claims
1. A method for preparing a solar cell, characterized in that, Includes the following steps: A silicon substrate is provided, and a first step texturing and a second step texturing are performed sequentially on the silicon substrate to form a textured surface on at least one side surface of the silicon substrate. The processing time of the first step texturing is less than the processing time of the second step texturing, and the concentration of the texturing solution used in the first step texturing is greater than the concentration of the texturing solution used in the second step texturing.
2. The preparation method according to claim 1, characterized in that, The texturing solution is a mixture comprising a first alkaline solution and a nucleating additive, wherein the concentration of the first alkaline solution is 1-5 wt%.
3. The preparation method according to claim 1, characterized in that, The processing time for the first step of the flocking process is 20-90 seconds.
4. The preparation method according to claim 1, characterized in that, The texturing solution is a mixture comprising a second alkaline solution and a nucleating additive, wherein the concentration of the second alkaline solution is 0.5-2.5 wt%.
5. The preparation method according to claim 1, characterized in that, The second step of the flocking process takes 5-15 minutes.
6. The preparation method according to claim 1, characterized in that, The temperature of the first step of the flocking process is 70-85℃, and the temperature of the second step of the flocking process is 70-80℃.
7. A solar cell, characterized in that, The solar cell, prepared by the method according to any one of claims 1 to 6, comprises: A silicon substrate, wherein at least one surface of the silicon substrate has a textured surface, the textured surface includes a plurality of microstructures, the bottom surface of the microstructures is polygonal and the diagonal length of the bottom surface is less than 1.5 μm, and the height of the microstructures is less than 1.1 μm.
8. The solar cell according to claim 7, characterized in that, The diagonal length of the bottom surface of the microstructure is less than 0.1-1 μm, and the height of the microstructure is less than 0.1-1 μm.
9. The solar cell according to claim 7, characterized in that, The variance of the diagonal of the bottom surface of the microstructure is less than 0.
1.
10. The solar cell according to claim 7, characterized in that, The surface reflectivity of the silicon substrate having the textured surface is less than 10%.
11. The solar cell according to any one of claims 7 to 10, characterized in that, The solar cell also includes an antireflective coating located on the side of the silicon substrate having the textured surface.
12. The solar cell according to claim 11, characterized in that, The thickness uniformity of the antireflective film is less than 10%.
13. The solar cell according to claim 11, characterized in that, The refractive index uniformity of the antireflective coating is less than 1.2%.