Solar cell, preparation method thereof and cell module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a solar cell, a preparation method thereof and a cell module. The solar cell includes: a substrate including a first region and a second region; the first passivation layer is located on the side, away from the substrate, of the first doped region, and the second passivation layer is located on the side, away from the first doped region, of the substrate; the first electrode is located at one side, far away from the second doped region, of the third passivation layer; the tunneling layer is located at one side, far away from the second doped region, of the substrate; the doped conductive layer is located at one side, far away from the substrate, of the tunneling layer; the fourth passivation layer is located at one side, far away from the tunneling layer, of the doped conductive layer; the second electrode is located on the side, away from the doped conductive layer, of the fourth passivation layer. The minimum distance between the first doped region and the second passivation layer is smaller than the minimum distance between the second doped region and the tunneling layer. The solar cell provided by the embodiment of the invention at least can improve the performance of the solar cell.

Description

Technical Field

[0001] This application relates to the photovoltaic field, and in particular to a solar cell, a method for preparing a solar cell, and a cell module. Background Technology

[0002] Solar cells, also known as photovoltaic cells, are devices that directly convert sunlight into electrical energy. Their working principle is based on the photovoltaic effect in semiconductor physics. When sunlight shines on a semiconductor material, photon energy is absorbed and excites electrons to jump to the conduction band, thus generating free electron-hole pairs. These charge carriers move under the influence of an electric field inside the semiconductor, forming an electric current, and thus generating electrical energy.

[0003] Currently, the main solar cell technologies on the market include IBC cells, TOPCon cells, PERC cells, and heterojunction cells (HJT). These cells, through carefully designed multilayer film structures and material properties, aim to minimize optical losses during the light-to-electricity conversion process, while effectively reducing carrier recombination on the silicon substrate surface and within the substrate, thereby improving the photoelectric conversion efficiency of the cells.

[0004] However, the performance of solar cells in existing technologies is still not ideal. Summary of the Invention

[0005] This application provides a solar cell, a method for preparing a solar cell, and a battery module, which at least helps to improve the performance of the solar cell.

[0006] According to some embodiments of this application, one aspect of this application provides a solar cell, including a substrate, wherein the substrate includes a first region and a second region; a first doped region, a first passivation layer, and a second passivation layer located in the first region, the first passivation layer being located on the side of the first doped region away from the substrate, and the second passivation layer being located on the side of the substrate away from the first doped region; a second doped region, a third passivation layer, a first electrode, a tunneling layer, a doped conductive layer, a fourth passivation layer, and a second electrode located in the second region, wherein the third passivation layer is located on the side of the second doped region away from the substrate, the first electrode is located on the side of the third passivation layer away from the second doped region, the tunneling layer is located on the side of the substrate away from the second doped region, the doped conductive layer is located on the side of the tunneling layer away from the substrate, the fourth passivation layer is located on the side of the doped conductive layer away from the tunneling layer, and the second electrode is located on the side of the fourth passivation layer away from the doped conductive layer, the minimum distance between the first doped region and the second passivation layer is a first distance, the minimum distance between the second doped region and the tunneling layer is a second distance, and the first distance is less than the second distance.

[0007] In some embodiments, the absolute value of the difference between the first distance and the second distance is 2~15μm.

[0008] In other embodiments, the junction depth of the first doped region is greater than the junction depth of the second doped region.

[0009] In some other embodiments, the junction depth of the first doped region is 0.5~5μm, and the junction depth of the second doped region is 0.1~2μm.

[0010] In some other embodiments, the sheet resistance of the first doped region is greater than that of the second doped region.

[0011] In other embodiments, the sheet resistance of the first doped region is 100~500 Ω / square, and the sheet resistance of the second doped region is 500~1000 Ω / square.

[0012] In some other embodiments, the doping concentration of the first doped region is less than that of the second doped region.

[0013] In some other embodiments, the doping concentration of the first doped region is 1×10⁻⁶. 15 ~1×10 19 at / cm 3 The doping concentration of the second doped region is 1×10⁻⁶. 18 ~1×10 23 at / cm 3 .

[0014] In other embodiments, the solar cell further includes: a first antireflection layer located on the side of the first passivation layer away from the first doped region; a second antireflection layer located on the side of the second passivation layer away from the substrate; a third antireflection layer located between the third passivation layer and the first electrode; and a fourth antireflection layer located between the fourth passivation layer and the second electrode.

[0015] In some other embodiments, the thickness of the doped conductive layer is 20-400 nm.

[0016] In some other embodiments, the thickness of the tunneling layer is 0.5~2nm.

[0017] According to some embodiments of this application, another aspect of this application provides a method for fabricating a solar cell, providing a substrate, wherein the substrate has a first surface and a second surface opposite to each other, the substrate including a first region and a second region; a diffusion layer and a BSG layer are sequentially formed on the first surface; the BSG layer and the diffusion layer in the first region are processed to remove the BSG layer and a portion of the diffusion layer to obtain a first doped region and a second doped region, wherein the remaining diffusion layer in the first region forms the first doped region, and the remaining diffusion layer in the second region forms the second doped region; a tunneling layer and a doped conductive layer are sequentially formed in the second region of the second surface; a first passivation layer, a second passivation layer, a third passivation layer, and a fourth passivation layer are formed in the first region of the first surface, the first region of the second surface, the second region of the first surface, and the second region of the second surface, respectively; a first electrode is formed on the side of the third passivation layer away from the second doped region; and a second electrode is formed on the side of the fourth passivation layer away from the doped conductive layer.

[0018] In some embodiments, the BSG layer and the diffusion layer in the first region are processed to remove the BSG layer and a portion of the diffusion layer to obtain a first doped region and a second doped region. This includes: performing a first laser treatment on the first region to diffuse ions in the diffusion layer into the substrate, wherein the first laser treatment is a red laser, the power of the first laser treatment is 5W~100W, and the scanning speed of the first laser treatment is 5000~40000mm / s; and etching the first region with an alkaline solution to remove the BSG layer and a portion of the diffusion layer, wherein the etching temperature is 50~90℃, the etching time is 10~400s, the volume of the alkaline solution is 1~30L, and the etching depth is 0.5~5μm.

[0019] According to some embodiments of this application, another aspect of this application provides a photovoltaic module, including a battery string connected by any of the solar cells described above; an encapsulation layer for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulation layer away from the battery string.

[0020] The technical solution provided in this application has at least the following advantages:

[0021] On the one hand, by differentiating the first and second regions of the solar cell, that is, by retaining part of the first doped region in the first region, the carrier recombination caused by doping with different elements such as B, P, and Ga in the first region can be eliminated, the open-circuit voltage can be increased, and thus the performance of the solar cell can be improved.

[0022] On the other hand, the minimum distance between the first doped region and the second passivation layer is smaller than the minimum distance between the second doped region and the tunneling layer, which can realize the localization design of the first region, reduce the parasitic absorption effect of polycrystalline silicon, increase the short-circuit current, and thus improve the performance of the solar cell. Attached Figure Description

[0023] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a solar cell provided in one embodiment of this application;

[0025] Figure 2 This is a schematic diagram of the structure of a solar cell provided in another embodiment of this application;

[0026] Figure 3 A schematic flowchart illustrating a method for fabricating a solar cell according to another embodiment of this application;

[0027] Figure 4 This is a schematic diagram of the structure corresponding to the process flow of a method for fabricating a solar cell according to an embodiment of this application;

[0028] Figure 5 This is a schematic diagram of the structure of a photovoltaic module provided in another embodiment of this application.

[0029] The above figures include the following reference numerals:

[0030] 10. Substrate; 101. First region; 102. Second region; 11. First doped region; 12. First passivation layer; 13. Second passivation layer; 14. Second doped region; 15. Third passivation layer; 16. First electrode; 17. Tunneling layer; 18. Doped conductive layer; 19. Fourth passivation layer; 20. Second electrode; 21. First antireflection layer; 22. Second antireflection layer; 23. Third antireflection layer; 24. Fourth antireflection layer; 25. Diffusion layer; 26. BSG layer; 40. Solar cell; 402. Conductive strip; 41. Encapsulation layer; 42. Cover plate. Detailed Implementation

[0031] As known from the background art, PN junctions are constructed by introducing specific impurity elements into semiconductor materials. Commonly used dopants include boron (B), phosphorus (P), and gallium (Ga). These elements can alter the conductivity of the semiconductor, forming P-type (holes as the primary charge carriers) and N-type (electrons as the primary charge carriers) regions. However, while increasing the doping concentration can enhance the electric field strength of the PN junction, which is beneficial for carrier separation and collection, excessively high doping concentrations can increase the defect density in the material, triggering Auger recombination. During this process, charge carriers interact with impurity atoms, releasing energy and significantly shortening the carrier lifetime, thereby reducing the open-circuit voltage and overall conversion efficiency of the battery.

[0032] To address the above problems, embodiments of this application provide a solar cell, such as... Figure 1 and Figure 2 As shown, it includes:

[0033] Substrate 10, wherein the substrate 10 includes a first region 101 and a second region 102;

[0034] Specifically, the substrate is responsible for absorbing sunlight and generating electron-hole pairs, i.e., photogenerated carriers, in the process. The substrate can be doped with elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As) to optimize its conductivity. The first and second regions are arranged along a first direction, which is perpendicular to the thickness direction of the substrate. Notably, subsequent manufacturing processes will form an electrode on at least one side of the substrate, which coincides with the projection of the second region onto the substrate. Along the first direction, the width of the second region can be designed to exceed the width of either the first or second electrode to ensure sufficient contact area and current conduction efficiency. The first region is located outside the projection range of the electrode onto the substrate and can also be defined as the remaining portion outside the second region. Although the first region does not directly participate in current conduction, it can provide passivation, reduce parasitic absorption, and control the recombination process of carriers, thereby improving the photoelectric conversion efficiency and stability of the battery. In some embodiments, the two opposing surfaces in the first region can be textured structures, which improve the bifaciality of the battery while increasing the open-circuit voltage and short-circuit current.

[0035] The first doped region 11, the first passivation layer 12, and the second passivation layer 13 are located in the first region 101. The first passivation layer 12 is located on the side of the first doped region 11 away from the substrate 10, and the second passivation layer 13 is located on the side of the substrate 10 away from the first doped region 11.

[0036] In practical applications, the first doped region and the first passivation layer are sequentially disposed in a first region of a first surface, and the second passivation layer is disposed in a first region of a second surface. The first doped region can be obtained by ion diffusion doping of the surface layer of the substrate, with the doped portion of the substrate becoming the first doped region. The first and second passivation layers can be single-layer or multilayer structures, and the materials of the first and second passivation layers can be one or more of the following: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0037] The second doped region 14, third passivation layer 15, first electrode 16, tunneling layer 17, doped conductive layer 18, fourth passivation layer 19, and second electrode 20 are located in the second region 102. The third passivation layer 15 is located on the side of the second doped region 14 away from the substrate 10. The first electrode 16 is located on the side of the third passivation layer 15 away from the second doped region 14. The tunneling layer 17 is located on the side of the substrate 10 away from the second doped region 14. The doped conductive layer 18 is located on the side of the tunneling layer 17 away from the substrate 10. The fourth passivation layer 19 is located on the side of the doped conductive layer 18 away from the tunneling layer 17. The second electrode 20 is located on the side of the fourth passivation layer 19 away from the doped conductive layer 18. The minimum distance between the first doped region 11 and the second passivation layer 13 is a first distance L1, and the minimum distance between the second doped region 14 and the tunneling layer 17 is a second distance L2. The first distance L1 is less than the second distance L2.

[0038] Specifically, the second doped region, the third passivation layer, and the first electrode are sequentially disposed in the second region of the first surface, and the tunneling layer, the doped conductive layer, and the fourth passivation layer are sequentially disposed in the second region of the second surface. The second doped region can be obtained by ion diffusion doping of the substrate surface, with the doped portion of the substrate becoming the second doped region. The materials of the first and second electrodes can include one or more of aluminum, silver, gold, nickel, molybdenum, or copper. The tunneling layer is located between the substrate and the doped conductive layer, serving to achieve interface passivation of the substrate surface, providing a chemical passivation effect, reducing interface states, and the tunneling layer can form a passivation contact layer together with the doped conductive layer. The material of the tunneling layer can be a dielectric material, such as any one of silicon oxide, magnesium fluoride, silicon oxide, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, and titanium oxide. The doped conductive layer can be a single-layer structure or a multi-layer structure. The aforementioned third and fourth passivation layers can be single-layer or stacked structures, and the materials of the third and fourth passivation layers can be one or more of the following: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0039] In the solar cell of this application, on the one hand, by differentiating the first region and the second region of the solar cell, that is, by retaining a portion of the first doped region in the first region, carrier recombination caused by doping with different elements such as B, P, and Ga in the first region can be eliminated, the open-circuit voltage can be increased, and thus the performance of the solar cell can be improved; on the other hand, the minimum distance between the first doped region and the second passivation layer is smaller than the minimum distance between the second doped region and the tunneling layer, which can realize the localization design of the first region, weaken the parasitic absorption effect of polycrystalline silicon, increase the short-circuit current, and thus improve the performance of the solar cell.

[0040] In some embodiments, the absolute value of the difference between the first distance and the second distance is 2 to 15 μm. Setting the difference between the first distance and the second distance within a suitable range can balance the quality of the substrate while further improving the performance of the solar cell.

[0041] In practical applications, the first distance is the minimum distance between the first doped region and the second passivation layer, which is the thickness of the substrate in the first region. The second distance is the minimum distance between the second doped region and the tunneling layer, which is the thickness of the substrate in the second region. The first distance is less than the second distance, which means that the thickness of the substrate in the first region is less than the thickness of the substrate in the second region.

[0042] In other embodiments, the junction depth of the first doped region is greater than that of the second doped region. The larger junction depth of the first doped region enhances the built-in electric field, facilitating faster separation and movement of electrons and holes towards the electrodes, reducing carrier recombination in the first region, and further improving open-circuit voltage and short-circuit current. The smaller junction depth of the second doped region reduces the absorption of incident light, particularly in the short-wavelength spectral range. This means more photons can directly reach the active region of the battery, rather than being absorbed near the surface, thereby further improving light utilization and the battery's short-circuit current.

[0043] In practical applications, those skilled in the art can set the junction depth of the first doped region and the second doped region according to the actual situation, as long as the junction depth of the first doped region is greater than the junction depth of the second doped region.

[0044] In some embodiments, the junction depth of the first doped region is 0.5~5 μm, and the junction depth of the second doped region is 0.1~2 μm. The junction depth of the first doped region being in the range of 0.5~5 μm ensures a relatively large junction depth, reducing carrier recombination in the first region, while also preventing excessively large junction depths, thus further avoiding increased optical losses due to excessive junction depth. The junction depth of the second doped region being in the range of 0.1~2 μm ensures a relatively small junction depth, while also preventing problems such as low charge separation efficiency and insufficient built-in electric field strength caused by excessively small junction depths.

[0045] Specifically, the junction depth of the first doped region can be 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, and 5 μm. The junction depth of the second doped region can be 0.1 μm, 0.3 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.9 μm, and 2 μm.

[0046] In some embodiments, the sheet resistance of the first doped region is greater than that of the second doped region. A higher sheet resistance in the first doped region allows for a reduction in its doping concentration, thereby providing better surface passivation, reducing surface recombination, and increasing carrier lifetime. A lower sheet resistance in the second doped region indicates good conductivity, which reduces the series resistance within the battery and thus improves the overall battery efficiency.

[0047] In other embodiments, the sheet resistance of the first doped region is 100~500Ω / square, and the sheet resistance of the second doped region is 500~1000Ω / square.

[0048] The sheet resistance of the first doped region can be 100 Ω / square, 200 Ω / square, 300 Ω / square, 400 Ω / square, and 500 Ω / square. The sheet resistance of the second doped region can be 500 Ω / square, 600 Ω / square, 700 Ω / square, 800 Ω / square, 900 Ω / square, and 1000 Ω / square.

[0049] In some embodiments, the doping concentration of the first doped region is lower than that of the second doped region. The lower doping concentration of the first doped region maintains a better passivation effect, further improving the open-circuit voltage and short-circuit current of the solar cell. The higher doping concentration of the second doped region results in a lower sheet resistance, increasing the carrier transport efficiency of the second region.

[0050] In some other embodiments, the doping concentration of the first doped region is 1×10⁻⁶. 15 ~1×10 19 at / cm 3 The doping concentration of the second doped region is 1×10⁻⁶. 18 ~1×10 23 at / cm 3 The doping concentration of the first doped region is 1×10⁻⁶. 15 ~1×10 19 at / cm 3 Within this range, the number of dopant elements in the first doped region is relatively small, maintaining a good passivation effect and further improving the open-circuit voltage and short-circuit current of the solar cell. The doping concentration of the second doped region is 1×10⁻⁶. 18 ~1×10 23 at / cm 3 Within this range, it is possible to ensure a high doping concentration in the second doped region, thereby giving it a smaller sheet resistance and increasing carrier transport efficiency; at the same time, it is possible to avoid an excessively high doping concentration on the top surface of the second doped region, meaning that the content of dopants in the second doped region will not be too high. This avoids the problem that too many dopants in the second doped region may become strong recombination centers, resulting in poor passivation ability of the second doped region.

[0051] For example, the doping concentration of the first doped region mentioned above can be 1×10⁻⁶. 15 at / cm 3 1×10 16 at / cm 3 1×10 17 at / cm 3 1×10 18 at / cm 3 and 1×10 19 at / cm 3 The doping concentration of the second doped region can be 1×10⁻⁶. 18 at / cm 3 1×10 19 at / cm 3 1×10 20 at / cm 3 1×1021 at / cm 3 1×10 22 at / cm 3 and 1×10 23 at / cm 3 .

[0052] In some other embodiments, such as Figure 2 As shown, the solar cell further includes: a first antireflection layer 21 located on the side of the first passivation layer 12 away from the first doped region 11; a second antireflection layer 22 located on the side of the second passivation layer 13 away from the substrate 10; a third antireflection layer 23 located between the third passivation layer 15 and the first electrode 16; and a fourth antireflection layer 24 located between the fourth passivation layer 19 and the second electrode 20. The arrangement of the first antireflection layer 21, the second antireflection layer 22, the third antireflection layer 23, and the fourth antireflection layer 24 can effectively reduce the reflectivity of the cell surface, thereby increasing the light transmittance and enhancing the light absorption rate of the cell.

[0053] Specifically, the materials of the first antireflection layer, the second antireflection layer, the third emission layer, and the fourth antireflection layer can be at least one of alumina, silicon nitride, and silicon oxynitride.

[0054] In some embodiments, the thickness of the doped conductive layer is 20-400 nm. The thickness of the doped conductive layer should not be too thick, as this may affect the overall thickness of the solar cell, hindering its miniaturization and thinning. Conversely, the thickness should not be too thin, as this may affect its conductivity. This optimal thickness setting of the doped conductive layer further ensures both the conductivity of the doped conductive layer and the requirement for a thinner solar cell.

[0055] For example, the thickness of the doped conductive layer can be 20nm, 60nm, 100nm, 140nm, 180nm, 220nm, 260nm, 300nm, 320nm, 360nm, and 400nm.

[0056] In other embodiments, the thickness of the tunneling layer is 0.5~2 nm. The thickness of the tunneling layer should not be too thick, as this may affect quantum tunneling of majority carriers in the tunneling dielectric layer, thus affecting the selective transport of charge carriers. Conversely, the thickness of the tunneling layer should not be too thin, as this may negatively impact the performance. The specific thickness settings of the first doped conductive layer and the tunneling layer can further ensure both the isolation effect of the isolation structure and the requirement for a thinner solar cell.

[0057] For example, the thickness of the tunneling layer can be 0.5 nm, 1 nm, 1.5 nm, and 2 nm.

[0058] Embodiments of this application also provide a method for manufacturing the above-described solar cell. Figure 3 This is a flowchart of a method for manufacturing a solar cell according to an embodiment of this application. Figure 3 As shown, the method includes the following steps:

[0059] Step S301, providing a substrate 10, wherein the substrate 10 has opposing first and second surfaces, and the substrate 10 includes a first region 101 and a second region 102, resulting in... Figure 4 The structure of (a);

[0060] Specifically, the substrate is responsible for absorbing sunlight and generating electron-hole pairs, i.e., photogenerated carriers, in the process. The substrate can be doped with elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As) to optimize its conductivity. The first and second regions are arranged along a first direction, which is perpendicular to the thickness direction of the substrate. Notably, subsequent manufacturing processes will form an electrode on at least one side of the substrate, which coincides with the projection of the second region onto the substrate. Along the first direction, the width of the second region can be designed to exceed the width of either the first or second electrode to ensure sufficient contact area and current conduction efficiency. The first region is located outside the projection range of the electrode onto the substrate and can also be defined as the remaining portion outside the second region. Although the first region does not directly participate in current conduction, it can provide passivation, reduce parasitic absorption, and control the recombination process of carriers, thereby improving the photoelectric conversion efficiency and stability of the battery. In some embodiments, the two opposing surfaces in the first region can be textured structures, which improve the bifaciality of the battery while increasing the open-circuit voltage and short-circuit current.

[0061] Step S302: A diffusion layer 25 and a BSG layer 26 are sequentially formed on the first surface to obtain the following result. Figure 4 (b) structure;

[0062] Specifically, the thickness of the aforementioned BSG layer can be 20~200nm.

[0063] Step S303: The BSG layer 26 and the diffusion layer 25 of the first region 101 are processed to remove the BSG layer 26 and a portion of the diffusion layer 25, resulting in a first doped region 11 and a second doped region 14. The remaining diffusion layer 25 of the first region 101 forms the first doped region 11, and the remaining diffusion layer 25 of the second region 102 forms the second doped region 14, resulting in... Figure 4 (c) structure;

[0064] Specifically, the BSG layer and the diffusion layer can be removed by laser etching.

[0065] In step S304, a tunneling layer 17 and a doped conductive layer 18 are sequentially formed in the second region 102 of the second surface, resulting in the following: Figure 4 The structure shown in (d);

[0066] Specifically, the tunneling layer is located between the substrate and the doped conductive layer, serving to achieve interface passivation of the substrate surface, providing a chemical passivation effect, reducing interface states, and the tunneling layer can form a passivation contact layer together with the doped conductive layer. The material of the tunneling layer can be a dielectric material, such as any one of silicon oxide, magnesium fluoride, silicon oxide, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, and titanium oxide. The doped conductive layer can be a single-layer structure or a multilayer structure.

[0067] Step S305: A first passivation layer 12, a second passivation layer 13, a third passivation layer 15, and a fourth passivation layer 19 are formed in the first region 101 of the first surface, the first region 101 of the second surface, the second region 102 of the first surface, and the second region 102 of the second surface, respectively, to obtain the following... Figure 4 The structure shown in (e);

[0068] Specifically, the first passivation layer, the second passivation layer, the third passivation layer, and the fourth passivation layer can be a single-layer structure or a stacked structure, and the materials of the first passivation layer, the second passivation layer, the third passivation layer, and the fourth passivation layer can be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0069] Step S306: A first electrode 16 is formed on the side of the third passivation layer 15 away from the second doped region 14, resulting in... Figure 4 The structure shown in (f);

[0070] Specifically, the material of the first electrode may include one or more of aluminum, silver, gold, nickel, molybdenum, or copper. In practical applications, the first electrode can be prepared by methods such as slurry coating, vapor deposition, or electroplating.

[0071] In step S307, a second electrode 20 is formed on the side of the fourth passivation layer 19 away from the doped conductive layer 18, resulting in... Figure 1 The structure shown.

[0072] Specifically, the material of the second electrode may include one or more of aluminum, silver, gold, nickel, molybdenum, or copper. In practical applications, the second electrode can be prepared by methods such as slurry coating, vapor deposition, or electroplating.

[0073] Through the above embodiments, on the one hand, by differentiating the first and second regions of the solar cell, that is, by retaining a portion of the first doped region in the first region, carrier recombination caused by doping with different elements such as B, P, and Ga in the first region can be eliminated, thereby increasing the open-circuit voltage and thus improving the performance of the solar cell; on the other hand, the minimum distance between the first doped region and the second passivation layer is smaller than the minimum distance between the second doped region and the tunneling layer, which can realize the localization design of the first region, weaken the parasitic absorption effect of polycrystalline silicon, increase the short-circuit current, and thus improve the performance of the solar cell.

[0074] In specific implementation, step S303 can be achieved through the following steps: Step S3031, performing a first laser treatment on the first region to diffuse ions in the diffusion layer to the substrate, wherein the first laser treatment is a red laser, the power of the first laser treatment is 5W~100W, and the scanning speed of the first laser treatment is 5000~40000mm / s; Step S3032, using an alkaline solution to etch the first region to remove the BSG layer and part of the diffusion layer, wherein the etching temperature is 50~90℃, the etching time is 10~400s, the volume of the alkaline solution is 1~30L, and the etching depth is 0.5~5μm. The parameter settings for the laser treatment and the etching treatment can further improve the accuracy of forming the first doped region and the second doped region.

[0075] Specifically, the power of the first laser treatment can be 5W, 25W, 50W, 75W, and 100W; the scanning speed of the first laser treatment can be 5000mm / s, 10000mm / s, 15000mm / s, 20000mm / s, 25000mm / s, 30000mm / s, 35000mm / s, and 40000mm / s; the etching temperature can be 50℃, 60℃, 70℃, 80℃, and 90℃; the etching time can be 10s, 100s, 200s, 300s, and 400s; the volume of the alkaline solution can be 1L, 10L, 20L, and 30L; and the etching depth can be 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, and 5μm.

[0076] like Figure 5 As shown, embodiments of this application also provide a photovoltaic module, including:

[0077] The battery string is formed by connecting multiple solar cells 40 of any one of the above embodiments;

[0078] Specifically, two adjacent battery strings can be electrically connected via conductive strips 402. In some embodiments, the electrodes of the same polarity of the solar cells 40 are oriented in the same direction, and the conductive strips 402 connect the electrodes of different polarities of two adjacent solar cells 40 respectively. In other embodiments, the solar cells 40 can also be arranged according to electrodes of different polarities, that is, the electrodes of multiple adjacent cells are arranged in the order of first polarity, second polarity, and first polarity, respectively, and the conductive strips 402 connect two adjacent cells on the same side. In some embodiments, there is no gap between the cells, that is, the cells overlap each other.

[0079] Encapsulation layer 41 is used to cover the surface of the battery string;

[0080] Specifically, the encapsulation layer 41 includes a first encapsulation layer and a second encapsulation layer. The first encapsulation layer covers either the front or back side of the solar cell string, and the second encapsulation layer covers the other side of the front or back side of the string. Specifically, the material of the encapsulation layer 41 can be at least one of organic encapsulation films such as polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer (EVA), polyvinyl octene elastomer (POE), or polyethylene terephthalate (PET). In practical applications, there is a gap between the first and second encapsulation layers during lamination, but after lamination, the first and second encapsulation layers together form the aforementioned encapsulation layer 41.

[0081] Cover plate 42 is used to cover the surface of the encapsulation layer 41 away from the battery string.

[0082] Specifically, the material of the cover plate 42 may include light-transmitting materials such as glass or plastic. Furthermore, the surface of the cover plate 42 facing the encapsulation layer 41 may be an uneven surface, thereby increasing the utilization rate of incident light. The cover plate 42 includes a first cover plate and a second cover plate, the first cover plate being disposed opposite to the first encapsulation layer, and the second cover plate being disposed opposite to the second encapsulation layer.

[0083] The solar cells described above in this application will be specifically described below with reference to specific embodiments and comparative examples.

[0084] Example 1

[0085] This embodiment provides a solar cell, including:

[0086] A substrate, wherein the substrate includes a first region and a second region;

[0087] The first doped region, the first passivation layer, and the second passivation layer are located in the first region. The first passivation layer is located on the side of the first doped region away from the substrate, and the second passivation layer is located on the side of the substrate away from the first doped region. The junction depth of the first doped region is 2.5 μm, the sheet resistance of the first doped region is 300 Ω / square, and the doping concentration of the first doped region is 1 × 10⁻⁶. 17 at / cm 3 ;

[0088] The second doped region, third passivation layer, first electrode, tunneling layer, doped conductive layer, fourth passivation layer, and second electrode are located in the second region described above. The third passivation layer is located on the side of the second doped region away from the substrate; the first electrode is located on the side of the third passivation layer away from the second doped region; the tunneling layer is located on the side of the substrate away from the second doped region; the doped conductive layer is located on the side of the tunneling layer away from the substrate; the fourth passivation layer is located on the side of the doped conductive layer away from the tunneling layer; and the second electrode is located on the side of the fourth passivation layer away from the doped conductive layer. The minimum distance between the first doped region and the second passivation layer is a first distance; the minimum distance between the second doped region and the tunneling layer is a second distance; the absolute value of the difference between the first distance and the second distance is 8 μm; the junction depth of the second doped region is 1 μm; the sheet resistance of the second doped region is 750 Ω / square; and the doping concentration of the second doped region is 1 × 10⁻⁶. 20 at / cm 3 .

[0089] Example 2

[0090] This application provides a solar cell, the only difference between this solar cell and Example 1 is that the absolute value of the difference between the first distance and the second distance is 15 μm.

[0091] Example 3

[0092] This application provides a solar cell, the only difference between this solar cell and Embodiment 1 is that the absolute value of the difference between the first distance and the second distance is 2 μm.

[0093] Example 4

[0094] This application provides a solar cell, the only difference from Embodiment 1 being that the junction depth of the first doped region is 5 μm and the junction depth of the second doped region is 2 μm.

[0095] Example 5

[0096] This application provides a solar cell, the only difference from Embodiment 1 being that the junction depth of the first doped region is 0.5 μm and the junction depth of the second doped region is 0.1 μm.

[0097] Example 6

[0098] This application provides a solar cell, the only difference from Embodiment 1 being that the sheet resistance of the first doped region is 500 Ω / square and the sheet resistance of the second doped region is 1000 Ω / square.

[0099] Example 7

[0100] This application provides a solar cell, the only difference from Embodiment 1 being that the sheet resistance of the first doped region is 100 Ω / square and the sheet resistance of the second doped region is 500 Ω / square.

[0101] Example 8

[0102] This application provides a solar cell, the only difference between this solar cell and Example 1 is that the doping concentration of the first doped region is 1×10⁻⁶. 19 at / cm 3 The doping concentration of the second doped region is 1×10⁻⁶. 23 at / cm 3 .

[0103] Example 9

[0104] This application provides a solar cell, the only difference between this solar cell and Example 1 is that the doping concentration of the first doped region is 1×10⁻⁶. 15 at / cm 3 The doping concentration of the second doped region is 1×10⁻⁶. 18 at / cm 3 .

[0105] Comparative Example 1

[0106] This application provides a solar cell, the only difference between this solar cell and Example 1 is that the absolute value of the difference between the first distance and the second distance is 16 μm.

[0107] Comparative Example 2

[0108] This application provides a solar cell, the only difference between this solar cell and Embodiment 1 is that the absolute value of the difference between the first distance and the second distance is 1 μm.

[0109] Comparative Example 3

[0110] This application provides a solar cell, the only difference from Embodiment 1 being that the junction depth of the first doped region is 6 μm and the junction depth of the second doped region is 3 μm.

[0111] Comparative Example 4

[0112] This application provides a solar cell, the only difference from Example 1 being that the junction depth of the first doped region is 0.1 μm and the junction depth of the second doped region is 0.05 μm.

[0113] Comparative Example 5

[0114] This application provides a solar cell, the only difference from Embodiment 1 being that the sheet resistance of the first doped region is 80 Ω / square and the sheet resistance of the second doped region is 400 Ω / square.

[0115] Comparative Example 6

[0116] This application provides a solar cell, the only difference from Embodiment 1 being that the sheet resistance of the first doped region is 700 Ω / square and the sheet resistance of the second doped region is 1200 Ω / square.

[0117] Comparative Example 7

[0118] This application provides a solar cell, the only difference between this solar cell and Example 1 is that the doping concentration of the first doped region is 1×10⁻⁶. 20 at / cm 3 The doping concentration of the second doped region is 1×10⁻⁶. 24 at / cm 3 .

[0119] Comparative Example 8

[0120] This application provides a solar cell, the only difference between this solar cell and Example 1 is that the doping concentration of the first doped region is 1×10⁻⁶. 14 at / cm 3 The doping concentration of the second doped region is 1×10⁻⁶. 17 at / cm 3 .

[0121] The performance of the solar cells using Examples 1-9 and Comparative Examples 1-8 was tested, and the test results are shown in Table 1:

[0122] Table 1

[0123]

[0124] The experimental data above show that the photoelectric conversion efficiency of Examples 1 to 9 is higher than that of Comparative Examples 1 to 8, and the fill factor of Examples 1 to 9 is higher than that of Comparative Examples 1 to 8, indicating that the solar cell of this application can reduce carrier recombination loss and improve photoelectric conversion efficiency. The experimental data also show that the open-circuit voltage and short-circuit current of Examples 1 to 3 are higher than those of Comparative Examples 1 and 2, indicating that the solar cell of this application can improve the open-circuit voltage and short-circuit current of the solar cell.

[0125] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0126] The solar cell of this application, on the one hand, by differentiating the first region and the second region of the solar cell, that is, by retaining a portion of the first doped region in the first region, can eliminate carrier recombination caused by the doping of heterogeneous elements such as B, P, and Ga in the first region, thereby increasing the open-circuit voltage and thus improving the performance of the solar cell; on the other hand, the minimum distance between the first doped region and the second passivation layer is smaller than the minimum distance between the second doped region and the tunneling layer, which can realize the localization design of the first region, weaken the parasitic absorption effect of polycrystalline silicon, increase the short-circuit current, and thus improve the performance of the solar cell.

[0127] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0128] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0129] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0130] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0131] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0132] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0133] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0134] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Moreover, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located therein.

[0135] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "part" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0136] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0137] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A solar cell, characterized in that, include: A substrate, wherein the substrate includes a first region and a second region; The first doped region, the first passivation layer, and the second passivation layer are located in the first region, wherein the first passivation layer is located on the side of the first doped region away from the substrate, and the second passivation layer is located on the side of the substrate away from the first doped region. The second region comprises a second doped region, a third passivation layer, a first electrode, a tunneling layer, a doped conductive layer, a fourth passivation layer, and a second electrode. The third passivation layer is located on the side of the second doped region away from the substrate. The first electrode is located on the side of the third passivation layer away from the second doped region. The tunneling layer is located on the side of the substrate away from the second doped region. The doped conductive layer is located on the side of the tunneling layer away from the substrate. The fourth passivation layer is located on the side of the doped conductive layer away from the tunneling layer. The second electrode is located on the side of the fourth passivation layer away from the doped conductive layer. The minimum distance between the first doped region and the second passivation layer is a first distance, and the minimum distance between the second doped region and the tunneling layer is a second distance. The first distance is less than the second distance.

2. The solar cell according to claim 1, characterized in that, The absolute value of the difference between the first distance and the second distance is 2~15μm.

3. The solar cell according to claim 1, characterized in that, The junction depth of the first doped region is greater than that of the second doped region.

4. The solar cell according to claim 3, characterized in that, The junction depth of the first doped region is 0.5~5μm, and the junction depth of the second doped region is 0.1~2μm.

5. The solar cell according to claim 1, characterized in that, The sheet resistance of the first doped region is greater than that of the second doped region.

6. The solar cell according to claim 5, characterized in that, The sheet resistance of the first doped region is 100~500Ω / square, and the sheet resistance of the second doped region is 500~1000Ω / square.

7. The solar cell according to claim 1, characterized in that, The doping concentration of the first doped region is less than that of the second doped region.

8. The solar cell according to claim 7, characterized in that, The doping concentration of the first doped region is 1×10 15 ~1×10 19 at / cm 3 The doping concentration of the second doped region is 1×10⁻⁶. 18 ~1×10 23 at / cm 3 .

9. The solar cell according to claim 1, characterized in that, The solar cell also includes: The first antireflection layer is located on the side of the first passivation layer away from the first doped region; The second antireflection layer is located on the side of the second passivation layer away from the substrate; The third anti-reflection layer is located between the third passivation layer and the first electrode; The fourth antireflection layer is located between the fourth passivation layer and the second electrode.

10. The solar cell according to claim 1, characterized in that, The thickness of the doped conductive layer is 20~400nm.

11. The solar cell according to claim 1, characterized in that, The thickness of the tunneling layer is 0.5~2nm.

12. A method for preparing a solar cell, characterized in that, include: A substrate is provided, wherein the substrate has opposing first and second surfaces, and the substrate includes a first region and a second region; A diffusion layer and a BSG layer are sequentially formed on the first surface; The BSG layer and the diffusion layer in the first region are processed to remove the BSG layer and part of the diffusion layer to obtain a first doped region and a second doped region, wherein the remaining diffusion layer in the first region forms the first doped region and the remaining diffusion layer in the second region forms the second doped region. A tunneling layer and a doped conductive layer are sequentially formed in a second region of the second surface; A first passivation layer, a second passivation layer, a third passivation layer, and a fourth passivation layer are formed in a first region of the first surface, a first region of the second surface, a second region of the first surface, and a second region of the second surface, respectively. A first electrode is formed on the side of the third passivation layer away from the second doped region; A second electrode is formed on the side of the fourth passivation layer away from the doped conductive layer.

13. The method for preparing a solar cell according to claim 12, characterized in that, The BSG layer and the diffusion layer in the first region are processed to remove the BSG layer and part of the diffusion layer, resulting in a first doped region and a second doped region, including: The first region is subjected to a first laser treatment to diffuse ions in the diffusion layer toward the substrate. The first laser treatment is a red laser, the power of the first laser treatment is 5W to 100W, and the scanning speed of the first laser treatment is 5000 to 40000 mm / s. The first region is etched with an alkaline solution to remove the BSG layer and part of the diffusion layer. The etching temperature is 50-90°C, the etching time is 10-400s, the volume of the alkaline solution is 1-30L, and the etching depth is 0.5-5μm.

14. A battery assembly, characterized in that, include: A battery string, formed by connecting solar cells according to any one of claims 1 to 11; An encapsulation layer is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulation layer away from the battery string.

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