Method for manufacturing solar cell, solar cell and photovoltaic module

Abstract

The application relates to a solar cell preparation method, a solar cell and a photovoltaic module, and belongs to the photovoltaic technical field. The solar cell preparation method comprises the following steps: providing a substrate, the first surface of the substrate has a pyramid structure, a doped conductive area is formed on the first surface, the doped conductive area is different from the doped element in the substrate in a conductive type, a silicon glass layer is formed on the side of the doped conductive area far from the first surface, laser processing is performed on the first area part of the first surface, low-concentration doped areas are formed in the substrate, meanwhile, the silicon glass layer in at least part of the tip part of the pyramid structure in the first area is broken to form notches, wet etching is performed on the first surface side, the notches can accelerate the etching rate of the surface film layer of the first area in the subsequent process, so that the efficiency of the prepared solar cell is improved.

Description

[0001] This application is a divisional application. The original application has the application number 202511902257.0 and the original application date is December 16, 2025. The entire contents of the original application are incorporated herein by reference. Technical Field

[0002] This application relates to the field of photovoltaic cell technology, specifically to a method for preparing a solar cell, a solar cell, and a photovoltaic module. Background Technology

[0003] A solar cell is a thin photovoltaic semiconductor wafer that generates electricity directly using sunlight. It is also known as a "solar chip" or "photovoltaic cell". As long as the illuminance meets certain conditions, it can instantly output voltage and generate current when there is a circuit. Summary of the Invention

[0004] In view of this, this application provides a method for preparing a solar cell, a solar cell, and a photovoltaic module, in order to solve the problem of low efficiency in the preparation of solar cells in the prior art.

[0005] The first aspect of this application provides a method for preparing a solar cell, the method comprising: A substrate is provided, the first surface of which has a pyramidal structure; A doped conductive region is formed on the first surface, wherein the conductivity type of the doped conductive region is different from that of the doped element in the substrate, and a silicon glass layer is formed on the side of the doped conductive region away from the first surface. Laser treatment is performed on a first region of the first surface to form a low-concentration doped region within the substrate, while simultaneously causing at least a portion of the silicon glass layer located at the apex of the pyramid structure in the first region to crack and form a gap. Wet etching is performed on the first surface side.

[0006] By irradiating a portion of the first region with a laser, the laser generates heat in that region. Since the volume of the pyramid apex in the first region is smaller than that of the pyramid base and it is closer to the laser source, the heat dissipation effect at the pyramid apex is poor. As a result, the energy received by the pyramid apex is much greater than that received by the pyramid base. That is, the pyramid apex in the irradiated area absorbs most of the laser energy. Therefore, the silicon glass layer at least partially located at the pyramid apex of the first region is more prone to breakage than other parts of the silicon glass layer. This allows the silicon glass layer at least partially located at the pyramid apex of the first region to break under the thermal effect of the laser, forming a gap. The gap can accelerate the subsequent etching rate of the surface film layer of the first region, thereby improving the efficiency of solar cell fabrication.

[0007] Simultaneously, laser irradiation of the first region enables the dopant elements in the doped conductive region of the first region to diffuse into the substrate under the thermal effect of the laser, forming a low-concentration doped region. This results in a lower average concentration of dopant elements in the low-concentration doped region of the first region compared to the average concentration of dopant elements in the doped conductive region of the second region. Since wet etching is required during the subsequent film-opening process of the first region, and the wet etching rate is affected by the doping concentration (inversely correlated within a certain range—the higher the concentration of doped conductive regions in the first region, the slower the etching rate), using laser irradiation to transform the doped conductive region of the first region into a low-concentration doped region is beneficial for improving the rate of wet etching of the first region in subsequent processes. This further improves the efficiency of removing the low-concentration doped region from the first region, thereby further improving the efficiency of solar cell fabrication. Therefore, this application's method of using laser irradiation of the first region can significantly increase the rate of subsequent film-opening of the first region, thereby greatly improving the efficiency of solar cell fabrication.

[0008] In this scheme, the laser is red light or green light, and / or; The laser is a continuous laser or the pulse width of the laser is nanoseconds.

[0009] In this scheme, the laser is red light, the laser is a continuous laser, and the power density range of the laser is 0.25 W / μm. 2 ~1w / μm 2 .

[0010] In this scheme, the laser is red light, the pulse width of the laser is nanoseconds, and the single-pulse energy density range of the laser is 3000 mJ / cm². 2 ~6500mJ / cm 2 .

[0011] In this scheme, the thickness of the doped conductive region is 100nm~1000nm, and the average concentration of the doped element in the doped conductive region is greater than 7×10⁻⁶. 19 atoms / cm 3 .

[0012] In this scheme, the average concentration of doped elements in the low-concentration doped region is less than 5 × 10⁻⁶. 19 atoms / cm 3 .

[0013] In this scheme, the thickness of the silicon glass layer is 5nm~50nm.

[0014] In this scheme, after laser processing of the first region of the first surface, the method for fabricating the solar cell further includes: performing a first etching process on the first surface to peel off the silicon glass layer in the first region, specifically including: The first surface is subjected to acid etching using an acid solution.

[0015] In this scheme, the acid solution is a hydrofluoric acid solution with a concentration of 0.01wt% to 10wt% and a process time of 5s to 600s.

[0016] In this scheme, after performing a first etching process on the first surface to peel off the silicon glass layer in the first region, the method for fabricating the solar cell further includes: performing a second etching process on the first surface to remove the silicon glass layer and the low-concentration doped region in the first region, specifically including: The first surface is subjected to alkaline etching treatment using an alkaline solution.

[0017] In this scheme, the alkaline solution is a sodium hydroxide solution with a concentration of 0.3wt%~1.4wt%, a process temperature of 70℃~85℃, and a process duration of 300s~800s.

[0018] In this scheme, after performing a second etching process on the first surface to remove the silicon glass layer and the low-concentration doped region in the first region, the method for fabricating the solar cell further includes: Remove the residual silicon glass layer on the first surface side.

[0019] A second aspect of this application provides a solar cell, which is prepared by the solar cell preparation method described above, and the solar cell comprises: A substrate having a first surface having a pyramidal structure; the first surface comprising alternating first and second regions. A doped conductive region is formed above or inside the second region.

[0020] A third aspect of this application provides a photovoltaic module, the photovoltaic module comprising: A battery string, wherein the battery string is composed of multiple solar cells as described above connected together; Encapsulation layer, the encapsulation layer being used to cover the surface of the battery string; A cover plate for covering the surface of the encapsulation layer away from the battery string.

[0021] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, 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 drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of the substrate provided in this application in a specific embodiment; Figure 2 This is a schematic diagram of the structure formed in a specific embodiment after performing step S2 in the method for preparing the solar cell provided in this application. Figure 3 This is a schematic diagram of the structure formed in a specific embodiment after performing step S3 in the method for preparing the solar cell provided in this application. Figure 4 This is a schematic diagram of the structure formed in a specific embodiment after performing step S4 in the method for preparing the solar cell provided in this application. Figure 5 A schematic diagram of the structure formed in a specific embodiment after performing steps S5 and S6 in the method for preparing the solar cell provided in this application; Figure 6 A scanning electron microscope image of the morphology of the first surface side of the structure formed after step S2 of the solar cell fabrication method provided in this application; Figure 7 for Figure 6 A magnified scanning electron microscope image of the morphology of a local area; Figure 8 A flowchart illustrating a specific embodiment of the method for fabricating the solar cell provided in this application; Figure 9 This is a schematic diagram of the structure of the solar cell provided in this application in a specific embodiment; Figure 10 This is a schematic diagram of the structure of the photovoltaic module provided in this application in a specific embodiment.

[0024] Figure label: 100-Solar Cell; 1-Base; 11-First surface; 11a - Second Zone; 11b - Zone 1; 111 - Pyramid structure; 2-Doped conductive region; 3-Silica glass layer; 31-Gap; 4-Low-concentration doped region; 5-Laser; 6-Front-side passivation layer; 7-Antireflection layer; 8-Backside doped region; 9-Backside passivation layer; 10-Tunneling oxide layer; 110-battery string; 120 - Encapsulation layer; 130 - Cover plate; Z - Thickness direction.

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0026] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0027] In the description of this application, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple" refers to two or more; the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0028] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0029] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0030] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0031] Based on this, this application provides a method for fabricating a solar cell 100, the solar cell 100, and a photovoltaic module, which is beneficial to improving the efficiency of fabricating the solar cell 100 and the photovoltaic module. The solar cell 100 fabricated by the method of this application can be applied to various battery structures, including but not limited to tunnel oxide passivated contact (TOPCon), interdigitated back contact (IBC), and passivated emitter rear cell (PERC), etc., without limitation.

[0032] like Figure 1 and Figure 8 As shown, the method for fabricating solar cell 100 includes: Step S1: Provide a substrate 1, the first surface 11 of which has a pyramid structure 111.

[0033] The substrate 1 is used to receive incident light and generate photogenerated carriers. In some embodiments, the substrate 1 is a silicon substrate 1, which may include one or more of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material of the substrate 1 may also be silicon carbide, organic materials, or multi-component compounds. Multi-component compounds may include, but are not limited to, perovskite, gallium arsenide, cadmium telluride, copper indium selenide, etc. Exemplarily, the substrate 1 in this application is a monocrystalline silicon substrate 1. The substrate 1 contains dopant elements, and the conductivity type of the dopant elements can be N-type or P-type. The N-type elements can be group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As), and the P-type elements can be group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In). For example, when the substrate 1 is a P-type silicon substrate, the conductivity type of its internal dopant elements is P-type. As another example, when the substrate 1 is an N-type silicon substrate, the conductivity type of its internal dopant elements is N-type. For example, in this embodiment of the application, substrate 1 is an N-type silicon substrate to improve the conversion efficiency of solar cell 100 and reduce manufacturing costs. Substrate 1 refers to a sheet-like structure that includes at least a silicon substrate. In some embodiments, substrate 1 may also include a tunneling layer and an intrinsic layer.

[0034] The substrate 1 with a pyramid structure 111 on the first surface 11 can be prepared by laser 5 or chemical etching.

[0035] Step S2: As Figure 2 As shown, a doped conductive region 2 is formed on the first surface 11, and a silicon glass layer 3 is formed on the side of the doped conductive region 2 away from the first surface 11. The doped conductive region 2 can be formed above or inside the first surface 11.

[0036] This application uses the example of a doped conductive region 2 formed above a first surface 11 for illustration.

[0037] It should be noted that, as Figure 1 As shown, the first surface 11 can be either the light-receiving surface or the back-lighting surface of the solar cell 100. When the first surface 11 is a light-receiving surface, for example, the doped conductive region 2 can be a P-type emitter layer formed by boron diffusion on the first surface 11, where the doping element can be boron. When the first surface 11 is a back-lighting surface, for example, the doped conductive region 2 can be an N-type doped conductive region formed by phosphorus diffusion on the first surface 11, where the doping element can be phosphorus. Specifically, the configuration can be tailored to actual needs, and this application does not impose any limitations on this.

[0038] This application takes the first surface 11 as the light-receiving surface as an example, and the doped conductive region 2 as a P-type emitter layer formed by boron expansion on the first surface 11 as an example for illustration.

[0039] In this step, a doped conductive region 2 and a silicon glass layer 3 are sequentially formed on the first surface 11. Taking the first surface 11 as the light-receiving surface as an example, the doped conductive region 2 can be a P-type emitter layer formed by boron diffusion on the first surface 11. The conductivity type of the doped conductive region 2 is different from that of the doped element in the substrate 1, so that the two can jointly form a PN junction structure. Exemplarily, the doped conductive region 2 can also be made of doped polycrystalline silicon, microcrystalline silicon, or amorphous silicon with a conductivity type opposite to that of the doped element in the substrate 1. When the substrate 1 is an N-type silicon substrate, a tunneling layer and a polycrystalline silicon, microcrystalline silicon, or amorphous silicon layer can be formed on the first surface 11 of the substrate 1 by low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD). The doped conductive region 2 and the silicon glass layer 3 are formed by doping the polycrystalline silicon, microcrystalline silicon, or amorphous silicon layer with P-type doped elements. The specific configuration can be set according to actual needs and is not limited here. Furthermore, when the P-type dopant is boron (B), the silicon glass layer 3 formed on the doped conductive region 2 is a borosilicate glass layer 3. The P-type dopant source can be BCl3 or BBr3, etc., and is not limited here.

[0040] Step S3: As Figure 3 , Figure 6 and Figure 7 As shown, the first region 11b of the first surface 11 is treated with laser 5 to form a low-concentration doped region 4 in the substrate 1, and at the same time, the silicon glass layer 3 in the first region 11b located at the top of the pyramid structure 111 is broken to form a gap 31.

[0041] Wet etching is performed on the first surface side, specifically: Step S4: Perform a first etching process on the first surface 11 to peel off the silicon glass layer 3 in the first region 11b; Step S5: Perform a second etching process on the first surface 11 to remove the silicon glass layer 3 and the low-concentration doped region 4 of the first region 11b. This helps to reduce Auger recombination in the first region 11b, giving the first region 11b a better passivation effect, improving the open-circuit voltage and fill factor of the solar cell 100, thereby improving the photoelectric conversion efficiency of the solar cell 100.

[0042] Step S3 of this application, such as Figure 3 and Figure 7As shown, when a portion of the first region 11b is irradiated by laser 5, the laser 5 generates heat on a portion of the first region 11b. Since the volume of the pyramid tip in the first region 11b is smaller than that of the pyramid base and is closer to the laser source 5, the heat dissipation effect of the pyramid tip is poor. As a result, the energy received by the pyramid tip is much greater than that received by the pyramid base. That is, the pyramid tip in the irradiated area absorbs most of the laser 5 energy. Therefore, the silicon glass layer 3 at least partially located at the pyramid tip of the pyramid structure 111 on the surface of the first region 11b is more prone to breakage than other locations of the silicon glass layer 3. This allows the silicon glass layer 3 at least partially located at the pyramid tip of the pyramid structure 111 on the surface of the first region 11b irradiated by laser 5 to break under the thermal effect of laser 5, forming a gap 31. The gap 31 can accelerate the subsequent etching rate of the film layer on the surface of the first region 11b, that is, accelerate the etching rate of subsequent steps S4 and S5, thereby improving the efficiency of fabricating the solar cell 100.

[0043] Simultaneously, in step S3, laser irradiation of the first region 11b enables the doped elements in the doped conductive region 2 of the first region 11b to diffuse into the substrate 1 under the thermal effect of laser 5, forming a low-concentration doped region 4. This results in the average concentration of doped elements in the low-concentration doped region 4 of the first region 11b being lower than the average concentration of doped elements in the doped conductive region 2 of the second region 11a. Since wet etching is required during the subsequent film-opening process of the first region 11b, and the wet etching rate is affected by the doping concentration, the wet etching rate and the doping concentration are inversely correlated within a certain range. That is, the higher the concentration of doped conductive region 2 in the first region 11b, the slower the etching rate. Therefore, using laser 5 to irradiate the doped conductive region 2 of the first region 11b into a low-concentration doped region 4 is beneficial to improving the rate of wet etching of the first region 11b in subsequent process steps, and further improving the efficiency of removing the low-concentration doped region 4 from the first region 11b, thereby further improving the efficiency of fabricating the solar cell 100. Therefore, by using laser 5 to irradiate part of the first region 11b, the rate of subsequent film opening of the first region 11b can be greatly improved, thereby greatly improving the efficiency of preparing the solar cell 100.

[0044] By performing step S4 first and then step S5, the silicon glass layer 3 of the first region 11b is preferentially stripped, which helps to accelerate the etching rate of the silicon glass layer 3 of the first region 11b and the low-concentration doped region 4 in the subsequent second etching process of step S5, thereby improving the efficiency of fabricating solar cell 100.

[0045] It should be noted that, in this application, the second region 11a refers to the area in the solar cell 100 where electrodes will be disposed, i.e., the metal region. The width of the metal region can be greater than or equal to the width of the actual grid line. The first region 11b is the area in the solar cell 100 other than the second region 11a, i.e., the non-metallic region.

[0046] like Figure 3 As shown, laser 5 is red or green light, and / or; Laser 5 is either a continuous laser or the pulse width of laser 5 is nanoseconds.

[0047] When laser 5 is red or green, it helps to improve the stability of laser irradiation and enhances the feasibility and reliability of the silicon glass layer 3 located at least part of the pyramid structure 111 in the first region 11b breaking to form a gap 31. When laser 5 is a continuous laser, it makes the output laser energy continuous and stable, so that laser 5 can apply a relatively stable thermal effect to part of the first region 11b, which is conducive to the instantaneous breaking of the silicon glass layer 3 located at least part of the pyramid structure 111 in the first region 11b to form a gap 31, and improves the reliability and stability of the diffusion of doped elements into the substrate 1 under the thermal effect of laser 5. When the pulse width of laser 5 is nanosecond, it helps to precisely control the laser energy, reduce the damage of laser 5 to the substrate 1, and at the same time, it helps to make the silicon glass layer 3 located at least part of the pyramid structure 111 in the first region 11b break rapidly to form a gap 31, and improves the reliability and stability of the diffusion of doped elements into the substrate 1 under the thermal effect of laser 5.

[0048] In some embodiments, laser 5 is red light; in still other embodiments, laser 5 is red light and is a continuous laser; in still other embodiments, laser 5 is red light and the pulse width of laser 5 is nanosecond; in some embodiments, laser 5 is green light; in still other embodiments, laser 5 is green light and is a continuous laser; in still other embodiments, laser 5 is green light and the pulse width of laser 5 is nanosecond; in still other embodiments, the pulse width of laser 5 is nanosecond; in still other embodiments, laser 5 is a continuous laser.

[0049] Specifically, in one possible implementation, such as Figure 3 As shown, laser 5 is red light, laser 5 is a continuous laser, and the power density range of laser 5 is 0.25 W / μm. 2 ~1w / μm 2 When the power density of laser 5 is in the range of 0.25 W / μm 2 ~1w / μm 2At the same time, controlling the power density of laser 5 to be moderate, so that the power density is not too high, is beneficial to reduce the damage caused by laser 5 to substrate 1, and is beneficial to increase short-circuit current and open-circuit voltage, thereby improving the photoelectric conversion efficiency of solar cell 100. At the same time, ensuring that the power density is not too low, it increases the thermal effect of laser 5 on the first region 11b, improves the efficiency of the silicon glass layer 3 located at least part of the pyramid structure 111 in the first region 11b to break and form a gap 31, and improves the reliability of the diffusion of doped elements into the substrate 1 under the thermal effect of laser 5, thereby improving the reliability of the doped conductive region 2 of the first region 11b to be transformed into a low-concentration doped region 4.

[0050] Optionally, the power density of laser 5 can be 0.25 W / μm. 2 0.3w / μm 2 0.4w / μm 2 0.5w / μm 2 0.6w / μm 2 0.7w / μm 2 0.8w / μm 2 0.9w / μm 2 or 1w / μm 2 It can also be other values ​​within the above range, and this embodiment does not limit it.

[0051] In another possible implementation, such as Figure 3 As shown, laser 5 is red light, the pulse width of laser 5 is nanoseconds, and the single-pulse energy density range of laser 5 is 3000 mJ / cm². 2 ~6500mJ / cm 2 When the single-pulse energy density of laser 5 is in the range of 3000 mJ / cm². 2 ~6500mJ / cm 2 At the same time, controlling the single-pulse energy density of laser 5 to be moderate, so that the single-pulse energy density is not too large, is beneficial to reducing the damage caused by laser 5 to substrate 1 and to improving short-circuit current and open-circuit voltage; at the same time, ensuring that the single-pulse energy density is not too small, improves the thermal effect of laser 5 on the first region 11b, improves the efficiency of the silicon glass layer 3 located at least part of the pyramid structure 111 in the first region 11b to break and form a gap 31, and improves the reliability of the diffusion of doped elements into the substrate 1 under the thermal effect of laser 5, thereby improving the reliability of the doped conductive region 2 to be transformed into a low-concentration doped region 4.

[0052] Optionally, the single-pulse energy density of laser 5 can be 3000 mJ / cm². 2 3500mJ / cm 2 4000mJ / cm 2 4500mJ / cm 2 5000mJ / cm2 5500mJ / cm 2 6000mJ / cm 2 Or 6500mJ / cm 2 It can also be other values ​​within the above range, and this embodiment does not limit it.

[0053] like Figure 2 As shown, the thickness of the doped conductive region 2 is 100 nm to 1000 nm, and the average concentration of the dopant element in the doped conductive region 2 is greater than 7 × 10⁻⁶. 19 atoms / cm 3 .

[0054] When the thickness of the doped conductive region 2 is 100nm~1000nm, the thickness of the doped conductive region 2 is moderate, ensuring that the thickness of the doped conductive region 2 is not too large. This improves the etching efficiency of the subsequent removal of the first region 11b, which is converted into a low-concentration doped region 4 via the doped conductive region 2, thereby improving the subsequent etching efficiency of the first region 11b and thus improving the efficiency of fabricating the solar cell 100. At the same time, ensuring that the thickness of the doped conductive region 2 is not too small ensures that the second region 11a has a better passivation effect and can form a better ohmic contact with the metal electrode, improving the fill factor and open-circuit voltage, thereby improving the photoelectric conversion efficiency of the solar cell 100.

[0055] Optionally, the thickness of the doped conductive region 2 can be 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm, or other values ​​within the above range. This embodiment does not limit this.

[0056] When the average concentration of doped elements in conductive region 2 is greater than 7 × 10 19 atoms / cm 3 At the same time, the average concentration of doped elements in the doped conductive region 2 is not too low. During the subsequent execution of steps S4 and S5, the corrosion rate of the wet etching solution on the second region 11a is reduced, so that the doped conductive region 2 in the second region 11a hardly undergoes etching, thereby improving the protection of the doped conductive region 2 in the second region 11a and improving the photoelectric conversion efficiency of the solar cell 100. At the same time, the average concentration of doped elements in the doped conductive region 2 is not too low, which is conducive to the formation of a better ohmic contact between the doped conductive region 2 in the second region 11a and the metal electrode, improving the fill factor and open circuit voltage, thereby further improving the photoelectric conversion efficiency of the solar cell 100.

[0057] Optionally, the average concentration of dopant elements in the doped conductive region 2 can be 7.2 × 10⁻⁶. 19 atoms / cm 3 7.3×1019 atoms / cm 3 7.5×10 19 atoms / cm 3 8×10 19 atoms / cm 3 8.5×10 19 atoms / cm 3 9×10 19 atoms / cm 3 9.5×10 19 atoms / cm 3 Or 1×10 20 atoms / cm 3 It can also be other values ​​within the above range, and this embodiment does not limit it.

[0058] In summary, when the thickness of the doped conductive region 2 is 100 nm to 1000 nm, and the average concentration of the dopant element in the doped conductive region 2 is greater than 7 × 10⁻⁶, the desired conductivity is achieved. 19 atoms / cm 3 At the same time, while ensuring that the second region 11a has a good ohmic contact, the etching efficiency of the first region 11b is improved, thereby improving the efficiency of fabricating the solar cell 100.

[0059] like Figure 3 As shown, the average concentration of doped elements in low-concentration doped region 4 is less than 5 × 10⁻⁶. 19 atoms / cm 3 In this application, the doping element in the low-concentration doped region 4 is the same as the doping element in the doped conductive region 2, that is, the doping element in the low-concentration doped region 4 is a single element. In this application, the doping element in the low-concentration doped region 4 can be any one of the group III elements such as boron (B), aluminum (Al), gallium (Ga) or indium gallium (In).

[0060] In other embodiments, when the substrate 1 is a P-type silicon substrate, the doping elements in the doped conductive region 2 and the low-concentration doped region 4 are all N-type elements, such as any one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb) or arsenic (As).

[0061] When the average concentration of doped elements in low-concentration doped region 4 is less than 5 × 10 19 atoms / cm 3This ensures that the average concentration of doped elements in the low-concentration doped region 4 is not too high. This is beneficial for increasing the difference between the average concentration of doped elements in the low-concentration doped region 4 of the first region 11b and the average concentration of doped elements in the conductive region 2 of the second region 11a. During subsequent first and second etching processes, this results in a significant difference between the etching rates of the etching solution on the first region 11b and the second region 11a. While minimizing etching in the second region 11a, this accelerates the etching rate of the etching solution on the silicon glass layer 3 of the first region 11b and the low-concentration doped region 4, thereby improving the film-opening efficiency of the first region 11b. Therefore, when the average concentration of doped elements in the low-concentration doped region 4 is less than 5 × 10⁻⁶, this method is effective. 19 atoms / cm 3 This is beneficial to improve the etching efficiency of the first region 11b while protecting the doped conductive region 2 of the second region 11a, thereby improving the efficiency of fabricating the solar cell 100 and increasing the conversion efficiency of the solar cell 100.

[0062] Optionally, the average concentration of doped elements in the doped conductive region 2 can be 1×10⁻⁶. 19 atoms / cm 3 1.5×10 19 atoms / cm 3 2×10 19 atoms / cm 3 2.5×10 19 atoms / cm 3 3×10 19 atoms / cm 3 3.5×10 19 atoms / cm 3 4×10 19 atoms / cm 3 4.5×10 19 atoms / cm 3 4.6×10 19 atoms / cm 3 4.8×10 19 atoms / cm 3 Or 4.9×10 19 atoms / cm 3 It can also be other values ​​within the above range, and this embodiment does not limit it.

[0063] It should be noted that the average concentration of the doped element is the average doping concentration of the doped element within a depth of 50 nm on the surface of the doped conductive region 2 or the low-concentration doped region 4.

[0064] The measurement process for the average concentration of doped elements in the doped conductive region 2 or the low-concentration doped region 4 is as follows: The relationship curve between the doping concentration and the doping depth of the doped conductive region 2 can be obtained using the electrochemical capacitance-voltage (ECV) method. Alternatively, the relationship curve between the doping concentration and the doping depth of the low-concentration doped region 4 can be obtained using the ECV method. Then, the doping concentration over a depth range of 50 nm is integrated to obtain the integrated area. Dividing the integrated area by the depth of 50 nm yields the average doping concentration of the doped conductive region 2 or the low-concentration doped region 4 over a depth range of 50 nm, thus obtaining the average concentration of doped elements in the doped conductive region 2 or the low-concentration doped region 4. Alternatively, the average doping concentration of the doped conductive region 2 or the low-concentration doped region 4 over a depth range of 50 nm can be directly read using certain equipment. Alternatively, an energy-dispersive X-ray spectroscopy (EDS) combined with a sample electron microscope (SEM / TEM) can be used to perform component analysis by detecting the characteristic X-rays excited when the electron beam bombards the sample, measuring the average concentration of dopant elements in the doped conductive region 2 or the low-concentration doped region 4. Alternatively, atomic probe tomography (APT) can be used, where a laser 5 and a high-voltage pulse evaporate the atoms at the top of the sample one by one, reconstructing the three-dimensional compositional distribution of the sample, and measuring the average concentration of dopant elements in the doped conductive region 2 or the low-concentration doped region 4. Furthermore, secondary ion mass spectrometry (SIMS) can be used, where a primary ion beam bombards the sample, sputtering "secondary ions," and then the composition of these ions is analyzed by a mass spectrometer to perform component analysis and measure the average concentration of dopant elements in the doped conductive region 2 or the low-concentration doped region 4. Specific settings can be configured according to actual needs and are not limited here.

[0065] Furthermore, since the doped elements in the doped conductive region 2 of the first region 11b in this application diffuse into the substrate 1 under the thermal effect of laser 5 to form a low-concentration doped region 4, the thickness of the low-concentration doped region 4 is greater than the thickness of the doped conductive region 2, that is, the thickness of the low-concentration doped region 4 is greater than 100nm~1000nm, and the concentration of doped elements gradually decreases beyond a depth of 50nm on the surface of the low-concentration doped region 4 and is less than 5×10 19 atoms / cm 3 This ensures that the low-concentration doped region 4 can still be quickly removed during the subsequent second etching process in step S5.

[0066] like Figure 2As shown, the thickness of the silicon glass layer 3 is 5nm~50nm. When the thickness of the silicon glass layer 3 is 5nm~50nm, the thickness is moderate, preventing it from becoming excessive. This improves the reliability of rapidly breaking the silicon glass layer 3 in the first region 11b, at least partially located at the apex of the pyramid structure 111, to form a notch 31 during step 2. Simultaneously, it helps reduce the process difficulty of subsequently removing the silicon glass layer 3 in the first region 11b and the silicon glass layer 3 in the second region 11a, thus improving the efficiency of the subsequent removal of the silicon glass layer 3 in the first region 11b and the second region 11a. The rate of the silicon glass layer 3 in region 11a is increased, thereby improving the efficiency of fabricating the solar cell 100. At the same time, the thickness of the silicon glass layer 3 is not too small. During the first and second etching processes, the silicon glass layer 3 in region 11a can effectively isolate the etching solution from contact with the doped conductive region 2 in region 11a, thereby improving the protective effect of the silicon glass layer 3 in region 11a on the doped conductive region 2 in region 11a. This is beneficial for forming excellent contact resistance in region 11a and improving the photoelectric conversion efficiency of the solar cell 100.

[0067] Optionally, the thickness of the doped conductive region 2 can be 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm or 50nm, or other values ​​within the above range. This embodiment does not limit this.

[0068] like Figure 4 As shown, after laser 5 processing of the first region 11b portion of the first surface 11, the method for fabricating the solar cell 100 further includes: performing a first etching process on the first surface 11 to peel off the silicon glass layer 3 of the first region 11b.

[0069] Step S4 specifically includes: using an acid solution to perform acid etching on the first surface 11. The acid solution can flow through the gap 31 formed in step S2 to the gap between the borosilicate glass layer 3 and the low-concentration doped region 4 in the first region 11b for rapid etching, so that the silicon glass layer 3 in the first region 11b is rapidly etched into a stripped state, which is beneficial to accelerate the rate of subsequent second etching process in step S5 to remove the silicon glass layer 3 and the low-concentration doped region 4 in the first region 11b, thereby improving the efficiency of fabricating the solar cell 100.

[0070] Meanwhile, since the silicon glass layer 3 in the second region 11a is not broken to form a gap 31, the acid solution of the first etching process can only etch and thin the silicon glass layer 3 in the second region 11a. If the thickness of the silicon glass layer 3 in the second region 11a is reduced to less than 80% of the thickness of the silicon glass layer 3 when it is not etched after the first etching process, the silicon glass layer 3 in the second region 11a can still effectively isolate the wet etching solution from the doped conductive region 2 in the second region 11a after the first etching process, thus protecting the doped conductive region 2 in the second region 11a.

[0071] It should be noted that peeling off the silicon glass layer 3 of the first region 11b, i.e., the silicon glass layer 3 of the first region 11b being in a peeled state, means that in some embodiments, the silicon glass layer 3 of the first region 11b has completely and slowly dissolved under the etching action of the acid solution, but the silicon glass layer 3 of the first region 11b has not completely desorbed from the low concentration doped region 4; in other embodiments, the silicon glass layer 3 of the first region 11b has not completely dissolved under the etching action of the acid solution, and the etching solution enters the gap between the silicon glass layer 3 of the first region 11b and the low concentration doped region 4 through the notch 31, preferentially etching the interface between the silicon glass layer 3 and the low concentration doped region 4, so that the interface is almost corroded, but a small part of the interface is still not completely corroded, and the silicon glass layer 3 of the first region 11b has not desorbed from the low concentration doped region 4.

[0072] In one possible implementation, the acid solution is a hydrofluoric acid solution with a concentration of 0.01wt% to 10wt% and a process duration of 5s to 600s. This is beneficial for precisely controlling and improving the etching rate of the first etching process, forming a good process window, and improving the quality of the fabricated solar cell 100.

[0073] When the concentration of the hydrofluoric acid solution is between 0.01wt% and 10wt%, even if a lower concentration is used, the concentration of the hydrofluoric acid solution is moderate and not too high. This helps to control the first etching process, prevents over-etching, and avoids etching damage to the substrate 1 and the doped conductive region 2 of the second region 11a. This is beneficial to improving the photoelectric conversion efficiency of the solar cell 100. At the same time, ensuring that the concentration of the hydrofluoric acid solution is not too low allows the silicon glass layer 3 to be etched quickly into a stripped state, improving the efficiency of the first etching process and thus improving the efficiency of the solar cell 100 fabrication.

[0074] Optionally, the concentration of the hydrofluoric acid solution can be 0.01wt%, 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, or 10wt%, or other values ​​within the above range. This embodiment does not limit this.

[0075] When the process duration of the first etching process is between 5s and 600s, the first etching process duration is moderate, ensuring it is not too short. This improves the reliability of the silicon glass layer 3 in the first region 11b being in the lift-off state smoothly, thereby increasing the efficiency of the subsequent second etching process in step S5. Simultaneously, ensuring the etching duration is not too long prevents over-etching during the first etching process, avoiding etching damage to the substrate 1 and the doped conductive region 2 in the second region 11a, which is beneficial for improving the photoelectric conversion efficiency of the solar cell 100.

[0076] Optionally, the process duration of the first etching process can be 5s, 50s, 100s, 150s, 200s, 250s, 300s, 350s, 400s, 450s, 500s, 550s or 600s, or other values ​​within the above range. This embodiment does not limit this.

[0077] like Figure 5 As shown, after performing a first etching process on the first surface 11 to peel off the silicon glass layer 3 in the first region 11b, the method for fabricating the solar cell 100 further includes: Step S5: Perform a second etching process on the first surface 11 to remove the silicon glass layer 3 and the low-concentration doped region 4 in the first region 11b, specifically including: Alkaline etching is performed on the first surface 11 using an alkaline solution. Through a second etching process, the silicon glass layer 3 and the low-concentration doped region 4 of the first region 11b are removed. This helps to reduce Auger recombination in the first region 11b, giving the first region 11b a better passivation effect, improving the open-circuit voltage and fill factor of the solar cell 100, thereby enhancing the photoelectric conversion efficiency of the solar cell 100.

[0078] In one possible implementation, the alkaline solution is a sodium hydroxide solution with a concentration of 0.3wt% to 1.4wt%, the process temperature is 70℃ to 85℃, and the process duration is 300s to 800s. This is beneficial for precisely controlling and improving the etching rate of the second etching process, forming a good process window, and improving the quality of the fabricated solar cell 100.

[0079] When the concentration of the sodium hydroxide solution is between 0.3 wt% and 1.4 wt%, the concentration is moderate, ensuring that it is not too high. This helps to control the second etching process, prevents over-etching, and avoids etching damage to the substrate 1 and the doped conductive region 2 of the second region 11a, thereby improving the photoelectric conversion efficiency of the solar cell 100. At the same time, the concentration of the sodium hydroxide solution is not too low, so as to quickly remove the silicon glass layer 3 and the low-concentration doped region 4 of the first region 11b, improve the efficiency of the second etching process, and thus improve the efficiency of the solar cell 100 fabrication.

[0080] Optionally, the concentration of the sodium hydroxide solution can be 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, or 1.4wt%, or other values ​​within the above range. This embodiment does not limit this.

[0081] When the process time of the second etching process is 300s to 800s, the second etching process is made moderate, ensuring that the etching time is not too short, thereby improving the feasibility and reliability of completely removing the silicon glass layer 3 and the low-concentration doped region 4 of the first region 11b. At the same time, ensuring that the etching time is not too long prevents over-etching during the second etching process, which helps to reduce the etching damage to the substrate 1 and the doped conductive region 2 of the second region 11a caused by the second etching process, and is beneficial to improving the photoelectric conversion efficiency of the solar cell 100.

[0082] Optionally, the process duration of the second etching process can be 300s, 350s, 400s, 450s, 500s, 550s, 600s, 650s, 700s, 750s or 800s, or other values ​​within the above range. This embodiment does not limit this.

[0083] When the process temperature of the second etching process is 70℃~85℃, the process temperature of the second etching process is moderate, so that the process temperature of the second etching process is not too high, the etching rate of the second etching process is not too fast, and the second etching process is not over-etched, so as to prevent etching damage to the substrate 1 and the doped conductive region 2 of the second region 11a, which is conducive to improving the photoelectric conversion efficiency of the solar cell 100. At the same time, the process temperature of the second etching process is not too low, which is conducive to the rapid removal of the silicon glass layer 3 and the low concentration doped region 4 of the first region 11b, improving the efficiency of the second etching process, and thus improving the efficiency of the fabrication of the solar cell 100.

[0084] Optionally, the process temperature for the second etching process can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C or 85°C, or other values ​​within the above range. This embodiment does not limit this.

[0085] like Figure 5 As shown, after performing a second etching process on the first surface 11 to remove the silicon glass layer 3 and the low-concentration doped region 4 in the first region 11b, the fabrication method of the solar cell 100 further includes: Step S6: Remove the residual silicon glass layer 3 on the first surface 11 side, that is, remove the silicon glass layer 3 of the second region 11a, so that the second doped conductive region 2 is exposed. This is beneficial for the doped conductive region 2 of the second region 11a to directly contact the metal electrode to form a better ohmic contact, improve the fill factor and open circuit voltage, thereby improving the photoelectric conversion efficiency of the solar cell 100.

[0086] This application also provides a solar cell 100, such as Figure 9 As shown, the solar cell 100 is prepared by the method for preparing the solar cell 100 in any of the above embodiments. The solar cell 100 includes: The substrate 1 has a first surface 11 along the thickness direction Z, and the first surface 11 has a pyramid structure 111; the first surface 11 includes an alternately distributed first region 11b and a second region 11a. Doped conductive region 2 is formed above or inside the second region 11a.

[0087] When the solar cell 100 is a tunneling oxide passivated contact cell, the first surface 11 is the light-receiving surface, and the side of the substrate 1 facing away from the first surface 11 along the thickness direction Z is the second surface. The substrate 1 at the second surface includes a full-area or localized tunneling oxide layer 10 and a back-side doped region 8. The doping type of the back-side doped region 8 is opposite to that of the doped conductive region 2. A front passivation layer 6 and an anti-reflection layer 7 are sequentially disposed on the side of the first surface 11, and a back passivation layer 9 is disposed on the side of the back-side doped region 8 facing away from the substrate 1 along the thickness direction Z of the substrate 1. When the solar cell 100 is fabricated by the fabrication method of the solar cell 100 in any of the above embodiments, the production efficiency of the solar cell 100 is improved, the production cost is reduced, and it is beneficial to make the doped conductive region 2 of the second region 11a directly contact the metal electrode to form a better ohmic contact, improve the fill factor and open-circuit voltage, thereby improving the photoelectric conversion efficiency of the solar cell 100. At the same time, it helps to reduce Auger recombination in the first region 11b, giving the first region 11b a better passivation effect, increasing the open-circuit voltage and fill factor of the solar cell 100, thereby further improving the photoelectric conversion efficiency of the solar cell 100.

[0088] This application also provides a photovoltaic module, such as Figure 10 As shown, the photovoltaic module includes a cell string 110, an encapsulation layer 120, and a cover plate 130. The cell string 110 is formed by connecting multiple solar cells 100 from any of the embodiments. The encapsulation layer 120 is used to cover the surface of the cell string 110, and the cover plate 130 is used to cover the surface of the encapsulation layer 120 away from the cell string 110. Since the solar cell 100 has the above-mentioned technical effects, the photovoltaic module including the solar cell 100 should also have the above-mentioned technical effects, which will not be elaborated further here.

[0089] Among them, such as Figure 10 As shown, the solar cell 100 is electrically connected in a single piece or in multiple segments to form multiple cell strings 110, which are electrically connected in series and / or parallel. Specifically, the multiple cell strings 110 can be electrically connected to each other via conductive links. An encapsulation layer 120 covers the front and back of the solar cell. Specifically, the encapsulation layer 120 can be an organic encapsulation film such as ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene copolymer elastomer (POE) film, polyethylene terephthalate (PET) film, or polyvinyl butyral (PVB). The cover plate 130 can be a light-transmitting cover plate such as a glass cover plate or a plastic cover plate. Specifically, the surface of the cover plate 130 facing the encapsulation layer 120 can be an uneven surface to increase the utilization rate of incident light.

[0090] The same or similar parts between the various embodiments in this specification can be referred to mutually. In particular, the device embodiments and terminal embodiments are basically similar to the method embodiments, so the description is relatively simple, and the relevant parts can be referred to the description in the method embodiments.

[0091] The above descriptions are merely specific implementations of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

Claims

1. A method for preparing a solar cell, characterized in that, The method for preparing the solar cell includes: A substrate is provided, the first surface of which has a pyramidal structure; A doped conductive region is formed on the first surface, wherein the conductivity type of the doped conductive region is different from that of the doped element in the substrate, and a silicon glass layer is formed on the side of the doped conductive region away from the first surface. Laser treatment is performed on a first region of the first surface to form a low-concentration doped region within the substrate, while simultaneously causing at least a portion of the silicon glass layer located at the apex of the pyramid structure in the first region to crack and form a gap. Wet etching is performed on the first surface side.

2. The method for preparing a solar cell according to claim 1, characterized in that, The laser is red or green light, and / or; The laser is a continuous laser or the pulse width of the laser is nanoseconds.

3. The method for preparing a solar cell according to claim 2, characterized in that, The laser is red light, it is a continuous laser, and its power density range is 0.25 W / μm. 2 ~1w / μm 2 .

4. The method for preparing a solar cell according to claim 2, characterized in that, The laser is red light, the pulse width is in nanoseconds, and the single-pulse energy density range is 3000 mJ / cm². 2 ~6500mJ / cm 2 .

5. The method for preparing a solar cell according to claim 1, characterized in that, The thickness of the doped conductive region is 100 nm to 1000 nm, and the average concentration of the doping element in the doped conductive region is greater than 7 × 10⁻⁶. 19 atoms / cm 3 .

6. The method for preparing a solar cell according to claim 1, characterized in that, The average concentration of dopant elements in the low-concentration doped region is less than 5 × 10⁻⁶. 19 atoms / cm 3 .

7. The method for preparing a solar cell according to claim 1, characterized in that, The thickness of the silicon glass layer is 5nm to 50nm.

8. The method for preparing a solar cell according to claim 1, characterized in that, After laser processing the first region of the first surface, the method for fabricating the solar cell further includes: performing a first etching process on the first surface to peel off the silicon glass layer in the first region, specifically including: The first surface is subjected to acid etching using an acid solution.

9. The method for preparing a solar cell according to claim 8, characterized in that, The acid solution is a hydrofluoric acid solution with a concentration of 0.01wt% to 10wt% and a process time of 5s to 600s.

10. The method for preparing a solar cell according to claim 8, characterized in that, After performing a first etching process on the first surface to remove the silicon glass layer in the first region, the method for fabricating the solar cell further includes: performing a second etching process on the first surface to remove the silicon glass layer and the low-concentration doped region in the first region, specifically including: The first surface is subjected to alkaline etching treatment using an alkaline solution.

11. The method for preparing a solar cell according to claim 10, characterized in that, The alkaline solution is a sodium hydroxide solution with a concentration of 0.3wt% to 1.4wt%, a process temperature of 70℃ to 85℃, and a process duration of 300s to 800s.

12. The method for preparing a solar cell according to claim 10, characterized in that, After performing a second etching process on the first surface to remove the silicon glass layer and the low-concentration doped region in the first region, the method for fabricating the solar cell further includes: Remove the residual silicon glass layer on the first surface side.

13. A solar cell, characterized in that, The solar cell is prepared by the method for preparing a solar cell according to any one of claims 1 to 12, wherein the solar cell comprises: A substrate having a first surface having a pyramidal structure; the first surface comprising alternating first and second regions. A doped conductive region is formed above or inside the second region.

14. A photovoltaic module, characterized in that, The photovoltaic module includes: A battery string, wherein the battery string is formed by connecting a plurality of solar cells as described in claim 13; Encapsulation layer, the encapsulation layer being used to cover the surface of the battery string; A cover plate for covering the surface of the encapsulation layer away from the battery string.

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