A solar cell and a method of manufacturing the same

Abstract

The application provides a solar cell and a preparation method, and belongs to the technical field of photovoltaics. The solar cell comprises a silicon substrate, a first surface of the silicon substrate is provided with first doped regions and second doped regions which are arranged alternately and have opposite conductive types, and an isolation region is arranged between the first doped regions and the second doped regions; the isolation region comprises at least one interval part and a co-doped region between the interval part and the first doped regions and / or the second doped regions, the co-doped region contains at least two kinds of doped elements of different conductive types, wherein, in the co-doped region, the doping concentration of the first doped elements gradually decreases and the doping concentration of the second doped elements gradually increases in the direction from the first doped regions to the second doped regions. The battery is designed in the manner of partially retaining the co-doped region and combining the internal concentration gradient, so that the carrier recombination at the edges of the doped regions is effectively reduced while the integrity of the doped regions is retained, and the photoelectric conversion efficiency of the battery is improved.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, and particularly relates to a solar cell and its preparation method. Background Technology

[0002] With the photovoltaic industry's increasing demands for battery efficiency and cost control, BC (Back Contact) battery technology has become an important technical route for realizing high-efficiency crystalline silicon solar cells.

[0003] In the prior art, in order to prevent conduction and leakage between the P-type and N-type doped regions on the back side of the back contact battery, laser grooving combined with wet etching is commonly used to form an isolation region. However, although this method achieves physical isolation, it inevitably has a negative impact on the active doped region itself.

[0004] Wet etching exposes the sidewalls of the doped region, forming a high-defect-density isolation interface. This severely damages the integrity of the doped region's edge, making it a highly efficient carrier recombination center and directly leading to a loss of open-circuit voltage. It also laterally erodes the doped region, reducing its effective collection area and thus impairing short-circuit current. This structural design reduces the electrical performance of the doped region, limiting further improvements in the photoelectric conversion efficiency of solar cells. Summary of the Invention

[0005] In view of this, the present disclosure provides a solar cell and a method for fabricating the same, which optimizes the edge structure of the doped region while retaining the co-doped region to protect the integrity of the doped region, thereby synergistically reducing recombination loss and improving open-circuit voltage and conversion efficiency.

[0006] In one aspect of this disclosure, a solar cell is provided, comprising: A solar cell, comprising: A silicon substrate having a first surface and a second surface disposed opposite to each other, the first surface having an alternately disposed first doped region and a second doped region, the first doped region and the second doped region having different conductivity types, and an isolation region being provided between the first doped region and the second doped region; The isolation region includes at least one spacer portion and a co-doped region located between the spacer portion and the first doped region and / or the second doped region; The co-doped region includes at least a first doping element of a first conductivity type and a second doping element of a second conductivity type. Within the co-doped region, the doping concentration of the first doping element gradually decreases and the doping concentration of the second doping element gradually increases in the direction from the first doping region to the second doping region.

[0007] In some embodiments, the co-doped region includes a first co-doped region and / or a second co-doped region.

[0008] In some embodiments, the first co-doped region and the first doped region are adjacent, and the second co-doped region and the second doped region are adjacent.

[0009] In some embodiments, the first co-doped region is in physical contact with the first doped region, and the second co-doped region is in physical contact with the second doped region.

[0010] In some embodiments, the first co-doped region and / or the second co-doped region comprises one or more combinations of dot-like, block-like, or discrete morphologies.

[0011] In some embodiments, the co-doped region has at least one of the same monocrystalline silicon, amorphous silicon, microcrystalline silicon, or polycrystalline silicon as the first doped region and / or the second doped region.

[0012] In some embodiments, the width of the first co-doped region and / or the second co-doped region in the first direction is 1 μm to 40 μm.

[0013] In some embodiments, the first conductivity type is P-type, the first doping element includes at least one element from group II IA, the second conductivity type is N-type, and the second doping element includes at least one element from group VA; or the first conductivity type is N-type, the first doping element includes at least one element from group VA, the second conductivity type is P-type, and the second doping element includes at least one element from group II IA.

[0014] In some embodiments, within the first co-doped region, the average doping concentration of the first doped element is higher than the doping concentration of the second doped element, and / or, within the second co-doped region, the average doping concentration of the second doped element is greater than the doping concentration of the first doped element.

[0015] In some embodiments, within the first co-doped region, the net doping concentration of the first dopant gradually decreases in the direction from the first doped region to the second doped region, and / or, within the second co-doped region, the net doping concentration of the second dopant gradually decreases in the direction from the second doped region to the first doped region.

[0016] In some embodiments, the peak concentration of the first dopant element in the first co-doped region is 1 × 10⁻⁶. 19 cm -3 -5×10 21 cm -3 The peak concentration of the second dopant element is 1×10⁻⁶. 17 cm -3 -1×10 19 cm -3And / or, within the second co-doped region, the peak concentration of the first dopant element is 1 × 10⁻⁶. 18 cm -3 -5×10 19 cm -3 The peak concentration of the second dopant element is 5 × 10⁻⁶. 19 cm -3 -5×10 20 cm -3 .

[0017] In some embodiments, the spacer includes a velvety surface, a micro-velvety surface, or a planar structure.

[0018] In some embodiments, the width of the spacer in the first direction is 20 μm to 400 μm.

[0019] In some embodiments, the spacer portion is a trench recessed from the first surface toward the inside of the silicon substrate.

[0020] In some embodiments, the depth of the spacer is not less than the thickness of the first doped region and / or the second doped region.

[0021] In one aspect of this disclosure, a method for fabricating a solar cell is provided, comprising: On the first surface of the substrate, a first doping element of a first conductivity type and a second doping element of a second conductivity type are simultaneously introduced. A first doped region and a second doped region are formed in an alternating pattern on a first surface, and an isolation region is formed between adjacent first doped regions and second doped regions. The isolation region is subjected to laser and wet processing to form a first co-doped region and / or a second co-doped region located between the spacer and the first doped region and / or the second doped region.

[0022] In one aspect of this disclosure, a photovoltaic module is provided, comprising the solar cell described in any of the preceding claims.

[0023] According to embodiments of this disclosure, a first doped region and a second doped region are alternately disposed on a first surface of a silicon substrate, and a co-doped region is disposed on the side close to the first doped region and / or the second doped region. Within the co-doped region, the doping concentration of the first dopant element gradually decreases and the doping concentration of the second dopant element gradually increases in the direction from the first doped region to the second doped region. The partially retained co-doped region can absorb laser energy during laser irradiation, reducing thermal damage to the doped region and protecting the integrity of the pure doped region. Simultaneously, the design of a gradual concentration change in the co-doped region creates a smooth concentration transition between the co-doped region and the doped region, effectively reducing carrier recombination in the edge region, improving carrier transport efficiency, and thus enhancing the photoelectric conversion efficiency of the back-contact battery.

[0024] Residual co-doped regions are set on both sides of the first and second doped regions, which can simultaneously optimize the recombination at the interface on both sides, further reduce leakage current and improve battery performance.

[0025] The first co-doped region is located on the side close to the first doped region, and the second co-doped region is located on the side close to the second doped region. This allows charge carriers to pass through efficiently and be collected by the corresponding electrodes, while strongly suppressing minority charge carriers from reaching the surface or bulk of the isolation region where recombination is highly risky, thereby significantly reducing edge recombination.

[0026] The gradual distribution of net doping concentration ensures a smooth electric field distribution within the space charge region, avoiding the generation of local strong electric field regions or electric field distortions within the transition region due to abrupt changes in net doping. This results in a uniform distribution of electric field intensity throughout the depletion region, which is beneficial for the directional drift and uniform collection of photogenerated carriers. It further reduces the recombination probability of carriers during their journey through the depletion region, providing a better electric field environment for improving the fill factor and short-circuit current.

[0027] The width of the first co-doped region and / or the second co-doped region in the first direction is 1 μm to 20 μm. If the width is too small, an effective gradient cannot be formed, and if the width is too large, it will affect the electrode layout and carrier collection path.

[0028] The presence of co-doped regions can prevent the etching solution from laterally corroding the doped regions, retain the effective area of ​​the doped regions, and improve the short-circuit current of solar cells.

[0029] Finally, by retaining the structure of some edge co-doped regions, the stringent requirements for etching time and uniformity are reduced, allowing for reasonable process fluctuations and significantly improving production yield and cost controllability. Attached Figure Description

[0030] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:

[0031] Figure 1 This is a schematic diagram of the structure of the solar cell described in the embodiments of this application. Figure 1 .

[0032] Figure 2 This is a schematic diagram of the structure of the solar cell described in the embodiments of this application. Figure 2 .

[0033] Figure 3 This is a schematic diagram of the structure of the solar cell described in the embodiments of this application. Figure 3 .

[0034] Figure 4 This is a schematic diagram of the structure of the solar cell described in the embodiments of this application. Figure 4 .

[0035] Figure 5 This is a schematic diagram of the structure of the solar cell described in the embodiments of this application. Figure 5 .

[0036] Figure 6 This is a schematic diagram of the structure of the solar cell described in the embodiments of this application. Figure 6 .

[0037] Figure 7 This is a schematic flowchart of the method for preparing the back contact battery cell provided in the embodiments of this application.

[0038] Figures 8-10 This is a schematic diagram of the structure corresponding to each step of the preparation method of the back contact battery cell provided in the embodiments of this application.

[0039] Figure 11 This is a schematic diagram of the structure of the solar cell described in Embodiment 1 of this application.

[0040] Figure 12 This is a schematic diagram of the structure of the solar cell described in Embodiment 2 of this application.

[0041] Figure 13 This is a schematic diagram of the structure of the solar cell described in Embodiments 3 and 4 of this application.

[0042] Figure 14 This is a schematic diagram of the structure of the solar cell described in the comparative examples of this application.

[0043] Explanation of reference numerals in the attached figures: 10-Silicon substrate, 11-First surface, 22-Second surface, 12-First doped region, 13-Second doped region, 14-Isolation region, 15-Spacer portion, 16-Co-doped region, 161-First co-doped region, 162-Second co-doped region, 30-First passivation layer, 40-Second passivation layer, 50-First antireflection layer, 60-Second antireflection layer, 71-First electrode, 72-Second electrode. Detailed Implementation

[0044] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The descriptions of the exemplary embodiments are merely illustrative and are in no way intended to limit the present disclosure or its application or use. The present disclosure may be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that the present disclosure will be thorough and complete, and will fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless specifically stated otherwise, the relative arrangement of components and steps, the composition of materials, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0045] The terms "first," "second," and similar words used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. Words such as "including" or "contains" mean that the element preceding the word encompasses the element listed after it, and do not exclude the possibility of encompassing other elements as well. Terms such as "above," "below," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, this relative positional relationship may also change accordingly.

[0046] In this disclosure, when a specific device is described as being located between a first device and a second device, an intermediary device may or may not be present between the specific device and the first or second device. When a specific device is described as being connected to other devices, the specific device may be directly connected to the other devices without an intermediary device, or it may be not directly connected to the other devices but have an intermediary device.

[0047] All terms used in this disclosure (including technical or scientific terms) have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in a general dictionary, such as a dictionary, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and not as having an idealized or highly formalized meaning, unless expressly defined herein.

[0048] This disclosure provides a solar cell and a method for fabricating the same, which aims to achieve electrical isolation while enhancing the passivation quality of the sidewalls of the doped region and improving photoelectric conversion efficiency.

[0049] Figure 1 This is a schematic diagram of the structure of some embodiments of solar cells according to the present disclosure.

[0050] refer to Figure 1 This disclosure provides a solar cell, including: a silicon substrate 10, the silicon substrate having a first surface 11 and a second surface 22 disposed opposite to each other, the first surface having an alternately disposed first doped region 12 and a second doped region 13, the first doped region 12 and the second doped region 13 having different conductivity types, and an isolation region 14 is provided between the first doped region and the second doped region 13. The isolation region 14 includes at least one spacer portion 15 and a co-doped region 16 located between the spacer portion 15 and the first doped region and / or the second doped region 13; The co-doped region 16 includes at least a first doping element of a first conductivity type and a second doping element of a second conductivity type. Within the co-doped region, the doping concentration of the first doping element gradually decreases and the doping concentration of the second doping element gradually increases in the direction from the first doping region to the second doping region.

[0051] like Figure 1 As shown, the solar cell in this embodiment includes a silicon substrate 10. The silicon substrate 10 can be a P-type silicon substrate, an N-type substrate, or an intrinsically conductive silicon wafer. The crystal type of the silicon substrate 10 can be monocrystalline or polycrystalline, etc. In this embodiment, no specific restrictions are placed on the material of the silicon substrate 10. In practical applications, those skilled in the art can select a suitable material as the substrate 10 as needed.

[0052] The silicon substrate 10 in this embodiment has a first surface 11 and a second surface 22 disposed opposite to each other. The first surface 11 is the back surface of the silicon substrate 10, and the second surface is the front surface of the silicon substrate 10. In other words, the solar cell disclosed in this embodiment is a back-contact solar cell.

[0053] like Figure 1 As shown, the first surface 11 of the solar cell in this embodiment has alternately arranged first doped regions 12 and second doped regions. The first doped region 12 and the second doped region 13 have different conductivity types, so as to collect the current generated by the silicon substrate 10 through the first doped region 12 and the second doped region 13. The width, thickness and surface morphology of the first doped region and the second doped region are not specifically limited, and can be the same or different.

[0054] It should be noted that in the embodiments of this application, the first doped region 12 and the second doped region 13 can both be one or more of monocrystalline silicon, polycrystalline silicon, amorphous silicon, and microcrystalline silicon. When the first doped region 12 is P-type doped, the second doped region 13 is N-type doped. When the first doped region 12 is N-type doped, the second doped region 13 is P-type doped. P-type doping generally contains Group 12IA elements. N-type doping generally contains Group 15VA elements.

[0055] Similarly, it is understandable that when the first doping element is a p-type doped group II IA element, the second doping element can be an n-type doped group VA element; and when the first doping element is an n-type doped group VA element, the second doping element can be a p-type doped group II IA element.

[0056] In this embodiment, the first doped region 12 can be doped with one element or with at least two elements with opposite charges. Similarly, the second doped region 13 can also be doped with one element or with at least two elements with opposite charges. In this embodiment, there are no excessive restrictions on the specific type and variety of doped elements in the first doped region 12 and the second doped region 13, as long as the polarities of the first doped region 12 and the second doped region 13 are opposite. In practical applications, those skilled in the art can set the specific type and variety of doped elements in the first doped region 12 and the second doped region 13 as needed.

[0057] like Figure 1 As shown, in this embodiment of the solar cell, an isolation region 14 is provided between the first doped region 12 and the second doped region 13; the isolation region 14 includes at least one spacer portion 15. The spacer portion 15 blocks the first doped region 12 and the second doped region 13, thereby preventing short circuits in the solar cell and improving the photoelectric conversion efficiency of the solar cell.

[0058] Furthermore, the solar cell in this embodiment includes a co-doped region 16 located between the spacer 15 and the first doped region and / or the second doped region 13. The co-doped region 16 contains at least a first doping element of a first conductivity type and a second doping element of a second conductivity type. Within the co-doped region 16, the doping concentration of the first doping element gradually decreases from the first doped region to the second doped region, while the doping concentration of the second doping element gradually increases. The partially retained co-doped region can absorb laser energy during laser irradiation, reducing thermal damage to the doped region and protecting the integrity of the pure doped region. Simultaneously, the gradual concentration transition between the co-doped region and the doped region creates a smooth concentration transition, effectively reducing carrier recombination in the edge region, improving carrier transport efficiency, and thus enhancing the photoelectric conversion efficiency of the back-contact cell.

[0059] refer to Figures 1-3 As shown, in some embodiments, the co-doped region 16 includes a first co-doped region 161 and / or a second co-doped region 162. The presence of the co-doped region can prevent the etching solution from laterally corroding the doped region, retain the effective area of ​​the doped region, and improve the short-circuit current of the solar cell. Moreover, retaining the structure of part of the edge co-doped region reduces the stringent requirements on etching time and uniformity, allows for reasonable process fluctuations, and significantly improves production yield and cost controllability.

[0060] It is understandable that if the first co-doped region 161 and the second co-doped region 162 exist simultaneously, the composite at both sides of the interface can be optimized at the same time, further reducing leakage current and improving the battery's voltage resistance.

[0061] refer to Figures 1-3 As shown, in some embodiments, the first co-doped region 161 is located on the side closer to the first doped region 12, and the second co-doped region 162 is located on the side closer to the second doped region 13. The first co-doped region being located on the side closer to the first doped region and the second co-doped region being located on the side closer to the second doped region allows carriers to pass through efficiently and be ultimately collected by the corresponding electrode, while strongly suppressing minority carriers from reaching the surface or bulk of the isolation region where recombination is highly risky, thereby significantly reducing edge recombination.

[0062] In some embodiments, the first co-doped region 161 is in physical contact with the first doped region 12, and the second co-doped region 162 is in physical contact with the second doped region 13.

[0063] It should be noted that, in some embodiments, the first co-doped region 161 and / or the second co-doped region 162 can be one or more combinations of dot-like, block-like, or discrete morphologies. It can be understood that the morphology, width, length, height, position, and number of the first and second co-doped regions can be set as needed, and can be the same or different.

[0064] In some embodiments, at least two elements with opposite electrical charges are simultaneously present within the first co-doped region 161 and / or the second co-doped region 162. The simultaneous presence of at least two elements with opposite electrical charges within the first co-doped region and / or the second co-doped region, together with the concentration gradient of the doped region, forms a built-in electric field that assists carrier transport. This electric field actively drives photogenerated carriers away from the interface and towards the collection electrode, thereby improving collection efficiency and filling factor while suppressing recombination.

[0065] In this embodiment, the dominant doping element type of the co-doped region is the same as that of the doping elements in the adjacent doped regions. Specifically, if the first doped region 12 is P-type doped, and a first co-doped region 161 exists, the doping concentration of the P-type doping element in the first co-doped region 161 is greater than the doping concentration of the N-type doping element. In other words, the doping type of the first co-doped region 161 is P-type, and its dominant doping element is the same as that of the adjacent first doped region 12. If a second co-doped region 162 exists, the doping concentration of the N-type doping element in the second co-doped region 162 is greater than the doping concentration of the P-type doping element. This allows for a concentration transition of the same type of dopant between the co-doped region and the doped region, which is beneficial for carrier transport.

[0066] It should be noted that in this embodiment, the first and second doping elements of the first doping region 12 and the second doping region 13 undergo lateral diffusion, forming an isolation region 14 where both doping elements coexist in the area between the first doping region 12 and the second doping region 13. That is, the isolation region 14 is a mixed region formed by the cross-diffusion of the two doping elements. After laser patterning and wet etching, the isolation region forms a residual part of the isolation region, namely the co-doped region 16 and the spacer 15. The first co-doped region 161 and the second co-doped region 162 are actually different parts of the same lateral diffusion. On the side near the first doping region 12, P-type doping elements dominate, forming a net P-type region; on the side near the second doping region 13, N-type doping elements dominate, forming a net N-type region; and in the middle of the lateral diffusion region, there is a compensation region with a similar concentration of P-type and N-type doping elements. However, after the isolation trench 14 is formed, the retained first co-doped region 161 and the second co-doped region 162 maintain the doping characteristics of the same type with their respective adjacent doping regions, thereby ensuring the doping continuity on both sides of the isolation structure.

[0067] According to some embodiments of the present invention, within the first co-doped region 161, the net doping concentration of the first dopant gradually decreases in the direction from the first doped region 12 to the second doped region 13, and / or, within the second co-doped region 162, the net doping concentration of the second dopant gradually decreases in the direction from the second doped region 13 to the first doped region 12. Setting the net doping concentration distribution to a gradual change within the co-doped region ensures a uniform distribution of electric field strength, which is beneficial for the directional drift and uniform collection of photogenerated carriers, further reducing the recombination probability of carriers, and providing a better electric field environment for improving the fill factor and short-circuit current.

[0068] Furthermore, in the co-doped region 16 near the first doped region 12 or the second doped region 13, the concentration of one dopant element is dominant, resulting in a better crystallization basis during high-temperature co-doping. However, towards the spacer region, the concentration of the other dopant element gradually increases, intensifying the lattice competition between the two impurities and gradually weakening the crystallization degree. The closer the concentrations of the two dopant elements in the co-doped region are to equilibrium, the more significant the lattice distortion and the lower the crystallinity. In short, the crystallinity of the first co-doped region 161 and / or the second co-doped region 162 near the spacer region 15 is lower than that away from the spacer region 15. The co-doped region near the isolation region has a lower crystallinity, making the material closer to amorphous or microcrystalline silicon, with higher resistance, which can more effectively block leakage current paths. The co-doped region near the doped region has a higher crystallinity, balancing resistance and recombination characteristics, and may form a beneficial bandgap at the interface, promoting selective transport of minority carriers.

[0069] In some embodiments, the crystallinity of the first co-doped region 161 is lower than that of the first doped region 12; the crystallinity of the second co-doped region 162 is lower than that of the second doped region 13. By having both the first and second co-doped regions coexist and have crystallinities lower than those of the doped regions, the electrical isolation effect can be enhanced while further reducing recombination at the edges of the doped regions.

[0070] In some embodiments, the co-doped region has at least one or more combinations of the same monocrystalline silicon, amorphous silicon, microcrystalline silicon, or polycrystalline silicon as the first doped region 12 and / or the second doped region 13.

[0071] In some embodiments, the width of the first co-doped region 161 and / or the second co-doped region 162 in the first direction is from 1 μm to 40 μm. For example, the width can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, etc. A width that is too small cannot form an effective gradient, while a width that is too large will affect the electrode layout and carrier collection path. Specifically, the widths of the first co-doped region 161 and the second co-doped region 162 can be the same, and the symmetrical design with the same width simplifies the process; the widths of the first co-doped region 161 and the second co-doped region 162 can also be different, and the widths of the residual regions on both sides can be optimized according to the differences in physical characteristics between the first doped region 12 and the second doped region 13 during the actual process by the technicians.

[0072] In some embodiments, the width of the spacer 15 in the first direction is from 20 μm to 400 μm. For example, the width can be 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, etc. The spacer at this width can isolate the first doped region 12 and the second doped region 13, preventing leakage.

[0073] refer to Figures 1-4 In some embodiments, the spacer 15 may be a velvety surface, a micro-velvety surface, or a planar structure.

[0074] In some embodiments, the spacer 15 is a trench recessed from the first surface toward the inside of the silicon substrate, providing more thorough electrical isolation and preventing leakage. (Reference) Figure 1 and Figure 5 As shown, in some embodiments, the depth of the spacer 15 is not less than the thickness of the first doped region 12 and / or the second doped region 13. It should be noted that the depth of the spacer 15 being equal to the thickness of the first doped region 12 and / or the second doped region 13 can effectively isolate the silicon layer while preserving as much contact area as possible between the polysilicon layer and the substrate, optimizing the back surface passivation effect, reducing damage to the silicon substrate, and facilitating carrier transport.

[0075] refer to Figure 5 As shown, in some embodiments, the depth of the spacer 15 is greater than the thickness of the first doped region 12 and / or the second doped region 13, which can effectively prevent leakage.

[0076] It should be noted that the reference Figure 6 As shown, in some embodiments, the depth of the spacer 15 is less than the thickness of the first doped region 12 and / or the second doped region 13, which can achieve local conductivity between the first doped region and the second doped region and prevent the hot plate effect from affecting the performance of the cell.

[0077] According to some embodiments of the present invention, with reference to Figure 11-13 The solar cell further includes a first functional layer 21 and a second functional layer 22. The first functional layer 21 and the second functional layer 22 may be composed of a passivation layer and / or an antireflection layer. For example, the first functional layer 21 includes a first passivation layer 30 and / or a first antireflection layer 50; the second functional layer includes a second passivation layer 40 and / or a second antireflection layer 60.

[0078] According to some embodiments of the present invention, the passivation layer or antireflection layer in the embodiments of this application can be a single-layer structure or a multi-layer structure. The passivation layer and the antireflection layer can exist alone or in a stacked combination. The passivation layer or antireflection layer includes one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, silicon carbide, amorphous silicon, and TCO.

[0079] According to some embodiments of the present invention, with reference to Figure 11-13 The solar cell also includes a first electrode 71 and a second electrode 72, wherein the first electrode 71 is in contact with the first doped region 12 and the second electrode 72 is in contact with the second doped region 13.

[0080] In one preferred embodiment, the thicknesses of the first passivation layer 30 and the second passivation layer 40 may be the same or different; the total thickness, stack thickness, or stacking order of the first antireflection layer 50 and the second antireflection layer may be the same or different.

[0081] In this embodiment, the first electrode 71 and the second electrode 72 can be made of metals, such as Ag, Cu, Al, Ni, Au, Zn, Sn, Pb, etc.; metal nitrides, such as TiN, etc.; metal carbides, such as TiC, etc.; or metal sulfides. In this embodiment, no specific limitations are placed on the materials used for the first and second electrodes. In practical applications, those skilled in the art can select appropriate materials as needed.

[0082] Reference Figures 8-10 The flowchart illustrates the method for preparing the solar cell described in the embodiments of this application.

[0083] like Figure 7 As shown in the embodiments of this application, a method for preparing a solar cell is disclosed, the method comprising: Step S1: Provide a silicon substrate, and simultaneously introduce a first dopant of a first conductivity type and a second dopant of a second conductivity type on a first surface of the substrate.

[0084] In this embodiment, the silicon substrate serves as the core component of the solar cell, converting solar energy into electrical energy. Exemplarily, the silicon substrate can be a P-type silicon substrate, an N-type silicon substrate, or an intrinsically conductive silicon wafer. The crystal type of the substrate can be monocrystalline or polycrystalline, etc. Of course, the substrate can also be other types. Here, no specific restrictions are placed on the specific type of substrate. In practical applications, those skilled in the art can select a suitable material as the substrate according to their needs.

[0085] It should be noted that, in this embodiment, the substrate needs to undergo surface treatment before providing the silicon substrate. This surface treatment includes polishing the first surface of the substrate and texturing the second surface. Of course, this surface treatment also includes steps such as removing damage and stains, which will not be listed here.

[0086] The substrate in this embodiment has a first surface and a second surface disposed opposite to each other, wherein the first surface is the back side of the solar cell and the second surface is the front side of the solar cell. In other words, the solar cell disclosed in this embodiment is a back-contact solar cell.

[0087] A first doping element and a second doping element are introduced at predetermined positions on the first surface of the solar cell to form a first doping region and a second doping region, respectively. The polarities of the first doping region and the second doping region are opposite.

[0088] Step S2: First doped regions and second doped regions are formed in an alternating pattern on the first surface, as well as an isolation region between adjacent first and second regions.

[0089] It should be noted that both the first and second doped regions can be one or more of monocrystalline silicon, polycrystalline silicon, amorphous silicon, and microcrystalline silicon. When the first doped region is a P-type doped region, the second doped region is an N-type doped region. When the first doped region is an N-type doped region, the second doped region is a P-type doped region. P-type doping typically involves group IIIA elements, while N-type doping typically involves group VA elements.

[0090] Specifically, in the embodiments of this application, the method for forming a first doped region and a second doped region on the first surface of the solar cell includes: A semiconductor layer is formed on the first surface of the silicon substrate; A first doping element is introduced into the first doping region, and a second doping element is introduced into the second doping region; A first doped region and a second doped region are formed, as well as an isolation region between the first doped region and the second doped region.

[0091] For example, in the embodiments of this application, the method for forming the semiconductor layer can be a chemical vapor deposition method, such as PECVD, APCVD, LPCVD, MOCVD, etc.; the semiconductor layer can also be single crystal silicon.

[0092] For example, in this embodiment of the application, a first doping element is introduced to form a first doped region and a second doping element is introduced to form a second doped region, such that the polarity of the second doped layer is opposite to that of the first doped layer. The methods for forming the first and second doped regions can include thermal diffusion, ion implantation, vapor deposition, laser doping, or coating with a paste. Those skilled in the art can choose a suitable doping method as needed.

[0093] It should be noted that, in the embodiments of this application, there is no specific limitation on the formation order of the first doped region and the second doped region. The first doped region can be formed first, followed by the second doped region. Alternatively, the second doped region can be formed first, followed by the first doped region. The first and second doped regions can also be formed simultaneously. There is no specific limitation on the thickness of the first and second doped regions; they can be the same or different. The substrates of the first and second doped regions can be on the same plane or have a height difference. In practical applications, those skilled in the art can choose according to their needs.

[0094] Specifically, in this embodiment, an amorphous silicon, microcrystalline silicon, or polycrystalline silicon layer can be formed on the first surface first, and then a doped source layer can be formed on its surface. Then, laser film opening is used to laser open the doped source region, and then high-temperature diffusion of the diffusion source is performed. The diffusion source and the doped source layer contain different doping elements. Through high-temperature diffusion, the elements in the doped source layer and the elements in the diffusion source can be diffused into the amorphous silicon, microcrystalline silicon, or polycrystalline silicon layer in the corresponding region to form the first doped region and the second doped region, respectively.

[0095] It should be noted that the laser energy during laser delamination may cause dopant elements in the doped source layer to enter the second doped region, meaning that the second doped region contains two doped elements with opposite polarities. Alternatively, a mask layer can be made on the surface of the doped source layer to prevent the laser energy during laser delamination from causing elements in the doped source layer to enter the second doped region.

[0096] For example, in the embodiments of this application, after the first doping element and the second doping region are formed in the first doping region, high temperature treatment is usually required to activate the first doping element and the second doping element in the first doping region and the second doping region. At the same time, the first doping element and the second doping element will diffuse laterally to form an isolation region, wherein the isolation region contains the first doping element and the second doping element.

[0097] Specifically, in the embodiments of this application, the method for forming a first doped region and a second doped region on the first surface of the solar cell further includes: The first doping element is diffused by first blocking a predetermined part of the second doped region using a masking process, and then the second doping element is diffused using a masking process. The diffusion region can be an amorphous silicon, microcrystalline silicon, or polycrystalline silicon layer, or it can be diffused directly on a single crystal silicon layer.

[0098] Step S3: Perform laser and wet processing on the isolation region to form a first co-doped region and / or a second co-doped region located between the spacer and the first doped region and / or the second doped region.

[0099] Specifically, in the embodiments of this application, the method for forming the co-doped region and the spacer includes: By using methods such as laser and wet etching, the semiconductor material in part of the isolation region is removed, the removed part of the isolation region forms the spacer, and the remaining isolation region is the co-doped region.

[0100] In this embodiment, the dominant doping element type of the co-doped region is the same as that of the doping elements in the adjacent doped regions. Specifically, if the first doped region is P-type doped, and a first co-doped region exists, the doping concentration of the P-type doping element in the first co-doped region is greater than the doping concentration of the N-type doping element. In other words, the doping type of the first co-doped region is P-type, and its dominant doping element is the same as that of the adjacent first doped region. If a second co-doped region exists, the doping concentration of the N-type doping element in the second co-doped region is greater than the doping concentration of the P-type doping element. This allows for a concentration transition of the same doping type between the co-doped region and the doped region, which is beneficial for carrier transport.

[0101] It should be noted that in the embodiments of this application, the first and second doping elements in the first and second doping regions undergo lateral diffusion, forming an isolation region where both doping elements coexist in the area between the first and second doping regions. That is, the isolation region is a mixed region formed by the cross-diffusion of the two doping elements. After laser patterning and wet etching, the isolation region forms residual portions, namely the co-doped region and the spacer. The first and second co-doped regions are actually different parts of the same lateral diffusion. On the side closer to the first doping region, P-type doping elements dominate, forming a net P-type region; on the side closer to the second doping region, N-type doping elements dominate, forming a net N-type region; and in the middle of the lateral diffusion region, there is a compensation region with relatively equal concentrations of P-type and N-type doping elements. However, after the isolation trench is formed, the retained first and second co-doped regions maintain the doping characteristic of the same type with their respective adjacent doping regions, thereby ensuring the doping continuity on both sides of the isolation structure.

[0102] Furthermore, in the co-doped region near the first or second doped region, the concentration of one dopant element is dominant, resulting in a better crystallization foundation during high-temperature co-doping. However, towards the spacer region, the concentration of the other dopant element gradually increases, intensifying the lattice competition between the two impurities and gradually weakening the crystallization. The closer the concentrations of the two dopant elements in the co-doped region are to equilibrium, the more significant the lattice distortion and the lower the crystallinity. In short, the co-doped region near the spacer region has a lower crystallinity, making the material closer to amorphous or microcrystalline silicon, with higher resistance, and can more effectively block leakage current paths. The co-doped region near the doped region has a higher crystallinity, balancing resistance and recombination characteristics, and may form a beneficial bandgap at the interface, promoting selective transport of minority carriers.

[0103] According to some embodiments of the present invention, by adjusting the laser-patterned area, a first co-doped region and a second co-doped region can be retained at the edges of the first doped region and the second doped region. The first co-doped region and the second co-doped region can coexist, or only one side of the first co-doped region or the second co-doped region can be retained. The first co-doped region is located on the side closer to the first doped region, and the second co-doped region is located on the side closer to the second doped region. This allows charge carriers to pass through efficiently and be collected by the corresponding electrodes, while strongly suppressing minority charge carriers from reaching the surface or bulk of the isolation region where there is a high risk of recombination, thereby significantly reducing edge recombination.

[0104] The presence of co-doped regions prevents lateral corrosion of the doped regions by the etching solution, preserves the effective area of ​​the doped regions, and improves the short-circuit current of the solar cell. Furthermore, retaining the structure of some edge co-doped regions reduces the stringent requirements for etching time and uniformity, allows for reasonable process fluctuations, and significantly improves production yield and cost controllability.

[0105] It is understandable that if the first co-doped region and the second co-doped region exist simultaneously, the composite at both interfaces can be optimized at the same time, further reducing leakage current and improving the battery's voltage resistance.

[0106] According to some embodiments of the present invention, the morphology of the first co-doped region and the second co-doped region can be set to be the same by adjusting the area patterned by the laser, or by adjusting the laser power, frequency, scanning speed, spot size and spot morphology and other related laser parameters. The symmetrical structure is beneficial to the collection of charge carriers. Alternatively, the morphologies of the first co-doped region and the second co-doped region can be set to be different, which relaxes the extreme requirements for equipment precision and improves the process window and yield.

[0107] Within the first co-doped region and / or the second co-doped region, at least two elements with opposite doping charges coexist. These elements, along with the concentration gradient of the doped region, form a built-in electric field that assists carrier transport. This electric field can actively drive photogenerated carriers away from the interface and flow towards the collection electrode, thereby improving collection efficiency and filling factor while suppressing recombination.

[0108] After laser treatment, the solar cell is subjected to wet etching to form co-doped regions and spacers. The wet etching process can be performed by directly treating the solar cell with a texturing solution to form a textured surface on the front side and a textured surface on the spacers. Alternatively, a mask can be formed on the back side of the solar cell first, and then the solar cell can be treated with a texturing solution to form a textured surface on the front side, while the spacers are planar or micro-textured.

[0109] The depth of the spacer is controlled by adjusting the concentration of the wet solution or the reaction time. The spacer is a recess into the silicon substrate, and the depth of the recess can be designed differently according to the needs of the technicians. If the depth of the recess is lower than the depth of the doped region, that is, the wet solution has not etched into the silicon substrate at the spacer, and there is still a residual isolation region below (co-doped), which can serve as a leakage channel to prevent the hot spot effect from damaging the cell. If the depth of the recess is equal to the depth of the doped region, that is, the wet solution just etches into the silicon substrate at the spacer, which can play a certain degree of isolation role, but there is still a risk of leakage. If the depth of the recess is greater than the thickness of the doped region, that is, the wet solution etches into the silicon substrate below the spacer, which can achieve electrical isolation between the first doped region and the second doped region.

[0110] By changing the range of laser patterning, the width of the co-doped region and the spacer can be altered. In some embodiments, the width of the first co-doped region 161 and / or the second co-doped region 162 in the first direction is from 1 μm to 40 μm. For example, this width can take values ​​of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, etc. A width that is too small cannot form an effective gradient, while a width that is too large will affect the electrode layout and carrier collection path. Specifically, the widths of the first and second co-doped regions can be the same, and this symmetrical design simplifies the process. Alternatively, the widths of the first and second co-doped regions can differ, allowing technicians to optimize the width of the residual regions on both sides based on the differences in physical properties between the first and second doped regions during actual operation. Furthermore, the co-doped regions of this invention have smaller widths, minimizing the potential risks posed by intrinsic material defects while achieving equivalent or even superior electrical functionality.

[0111] In some embodiments, the width of the spacer 15 in the first direction is from 20 μm to 400 μm. For example, the width can be 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, etc. The spacer at this width can isolate the first doped region 12 and the second doped region 13, preventing leakage.

[0112] The method for preparing solar cells disclosed in this application also includes: The process involves removing residual dopant sources from the surface of the solar cells and cleaning them. Further surface modification, such as etching, is also necessary. Etching removes surface dopant from various regions, eliminating areas with excessively high or low doping activation concentrations. Surfaces with excessively high activation concentrations can lead to Auger recombination regions, while surfaces with excessively low activation concentrations hinder subsequent contact between the surface metal and electrodes. These processes result in improved solar cell performance.

[0113] The method for preparing solar cells disclosed in this application also includes: A mask is formed on a first surface and a second surface. The mask layer can be a composite film composed of one or more of silicon nitride, silicon oxynitride, and silicon oxide. The thickness of the mask layer is 2nm-200nm.

[0114] In this embodiment of the application, after performing laser and wet processing on the isolation region to form a first co-doped region and / or a second co-doped region located between the spacer region and the first doped region and / or the second doped region, the method further includes: A surface passivation layer or antireflection layer is formed on the side of the first doped region, the second doped region, and the isolation region away from the substrate, and on the side of the second surface, on the first surface. A first electrode and a second electrode are formed within the surface passivation layer or antireflection layer, with the first electrode electrically connected to the first doped region and the second electrode electrically connected to the second doped region. This allows for the collection of charge carriers within the first doped layer and the transmission of current within the first doped layer via the first electrode, and the collection of charge carriers within the second doped layer and the transmission of current within the second doped layer via the second electrode.

[0115] In a preferred embodiment, during the surface passivation process, a surface passivation layer or antireflection layer can be formed simultaneously on the first surface and the side of the surface away from the substrate. This ensures that the structure of the surface passivation layer or antireflection layer corresponding to the first and second surfaces is completely identical.

[0116] In another preferred embodiment, during the surface passivation process, a surface passivation layer or antireflection layer can be formed first on the first surface and the side of the surface away from the substrate, and then a surface passivation layer or antireflection layer can be formed on the second surface and the side of the surface away from the substrate. The structure of the surface passivation layer or antireflection layer corresponding to the first and second surfaces can be set according to the needs of those skilled in the art.

[0117] It should be noted that the surface passivation layer or antireflection layer in the embodiments of this application can be a single-layer structure or a multi-layer structure. The surface passivation layer or antireflection layer includes one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, silicon carbide, amorphous silicon, and TCO. In the process of preparing the surface passivation layer or antireflection layer, atomic layer deposition (ALD), chemical vapor deposition (e.g., PECVD, APCVD, LPCVD, MOCVD, etc.), physical vapor deposition (evaporation, sputtering), and other methods can be used to prepare the surface passivation layer or antireflection layer.

[0118] For example, in the process of preparing a surface passivation layer or antireflection layer, an aluminum oxide passivation layer can be prepared first by atomic layer deposition (ALD), and then one or more silicon nitride layers can be formed on the aluminum oxide passivation layer by plasma enhanced chemical vapor deposition (PECVD).

[0119] The first and second electrodes in this embodiment can be made of metals, such as Ag, Cu, Al, Ni, Au, Zn, Sn, Pb, etc., or metal nitrides, such as TiN, or metal carbides, such as TiC, etc., or metal sulfides. In this embodiment, no particular restrictions are placed on the specific materials of the first and second electrodes. In practical applications, those skilled in the art can select appropriate materials as needed.

[0120] This application also discloses a photovoltaic module, which includes the solar cells described in the above embodiments.

[0121] It should be noted that in this embodiment, the photovoltaic module includes solar cells with the same structure as the solar cells described in the above embodiments, and their beneficial effects are similar, so they will not be repeated here.

[0122] Example 1 like Figure 11As shown, a solar cell includes a silicon substrate 10, a first surface 11, a second surface 22, a first doped region 12, a second doped region 13, an isolation region 14, a spacer 15, a first co-doped region 161, a first passivation layer 30, a second passivation layer 40, a first antireflection layer 50, a second antireflection layer 60, a first electrode 71, and a second electrode 72. As shown in the figure, the method for fabricating a solar cell in this embodiment includes the following steps:

[0123] 1. Select a P-doped N-type silicon wafer with a resistivity of 1.5 Ω cm and a thickness of 150 μm; use acid and alkali chemicals to remove organic contaminants and metallic impurities from the surface of the silicon wafer, and then etch and polish the surface of the single crystal silicon wafer.

[0124] 2. In a PECVD furnace tube, using N2O as the oxidant, at an oxidation temperature of 600℃ for 10 min, a tunneling oxide layer with a thickness of 1.5 nm is deposited on the first surface of the silicon substrate; using SiH4 as the reaction gas and Ar as the dilution gas, at a deposition temperature of 600℃ for 90 min, a polycrystalline silicon layer with a thickness of 250 nm is deposited on the surface of the tunneling oxide layer.

[0125] 3. In the PECVD furnace tube, using PH3, SiH4, N2O, and NH3 as deposition raw materials, the deposition temperature is 600℃ and the time is 50min. A phosphorus-containing silicon oxide layer with a thickness of 50nm is deposited on the polycrystalline silicon layer; a silicon oxide mask layer with a thickness of 100nm is deposited on the phosphorus-containing silicon oxide layer.

[0126] 4. Use a laser to open the silicon wafer. The laser parameters are set to a wavelength of 355 nm and an energy density of 0.5 J / cm². Then clean it in a cleaning machine by acid washing. After cleaning, dry it to expose the polycrystalline silicon layer on the back of the silicon wafer.

[0127] 5. The silicon wafer is placed in a boron-doped tube for doping at a temperature of 800℃ for 100 minutes. The boron doping source is BBr3. This forms a polycrystalline silicon region of the first conductivity type, also known as the first doped region, on the first surface of the silicon wafer. Simultaneously, the phosphorus-containing silicon oxide layer on the back side can serve as both a doping source for a second conductivity type impurity region, forming a second conductivity type impurity polycrystalline silicon region, and a boron doping barrier layer. During boron diffusion, the doping source of the second conductivity type impurity region diffuses into the polycrystalline silicon, forming the second doped region. The interdiffusion region between the first and second doped regions, representing the two conductivity types of impurities, forms an isolation region.

[0128] 6. The isolation region is patterned using a laser with a wavelength of 355 nm and an energy density of 2.5 J / cm². The region is then subjected to acid washing, alkali washing, water washing, and drying in a cleaning machine to form localized co-doped regions and spacers. The scanning path of the laser beam is controlled to deviate from the center of the initial isolation region and move closer to the second doped region. This allows the laser and etching solution to completely remove the material in the isolation region near the second doped region, forming a spacer that directly contacts the second doped region. On the first doped region side, some material from the initial isolation region is retained, forming the first co-doped region, with a residual width of 10 μm.

[0129] 7. Use a 1.3% NaOH solution for etching for 500 seconds to create a textured surface on the second surface of the silicon wafer and an isolation textured surface on the spacer portion of the first surface (not shown in the figure).

[0130] 8. Immerse the silicon wafer in 25% HF for 600 seconds to remove the phosphorus-containing silicon oxide layer, boron-containing silicon oxide layer, and mask layer; then perform RCA standard cleaning on the silicon wafer to remove surface contaminants.

[0131] 9. Using ALD atomic layer deposition with TMA as the precursor, a dense Al2O3 passivation layer with a thickness of 10nm is deposited on the first and second surfaces of the silicon wafer at a reaction temperature controlled at 300℃. Then, 100nm SiO2 antireflection layers are deposited on the front and back sides of the silicon wafer using PECVD. The passivation layer and the antireflection layer form a dielectric layer.

[0132] 10. Print Ag paste on the first surface of the silicon wafer, dry and sinter it to obtain a metal electrode.

[0133] Example 2 like Figure 12 As shown, a solar cell includes a silicon substrate 10, a first surface 11, a second surface 22, a first doped region 12, a second doped region 13, an isolation region 14, a spacer 15, a second co-doped region 162, a first passivation layer 30, a second passivation layer 40, a first antireflection layer 50, a second antireflection layer 60, a first electrode 71, and a second electrode 72. As shown in the figure, the method for fabricating a solar cell in this embodiment includes the following steps: The method is carried out in accordance with Example 1, except that in step 6, the scanning path of the laser beam is controlled to deviate from the center of the initial isolation region and get closer to the second doped region. In this way, the laser and the etching solution completely remove the material of the isolation region near the second doped region, forming a spacer that is in direct contact with the second doped region. On the second doped region side, the material of the initial isolation region is partially retained to form a second co-doped region with a width of 10 μm.

[0134] Example 3 like Figure 13 As shown, a solar cell includes a silicon substrate 10, a first surface 11, a second surface 22, a first doped region 12, a second doped region 13, an isolation region 14, a spacer 15, a first co-doped region 161, a second co-doped region 162, a first passivation layer 30, a second passivation layer 40, a first antireflection layer 50, a second antireflection layer 60, a first electrode 71, and a second electrode 72. As shown in the figure, the method for fabricating a solar cell in this embodiment includes the following steps: The method is performed according to Example 1, except that in step 6, the scanning path of the laser beam is controlled to roughly follow the centerline of the initial isolation region. However, by optimizing the laser energy density and etching formula, it is ensured that only the material in the central part is removed, while some of the initial isolation region material is retained on both sides of the groove. In this way, the laser and etching solution completely remove the material in the middle part of the isolation region, forming a spacer, while on the first doped region and the second doped region side, the material of the initial isolation region is partially retained, forming the first co-doped region and the second co-doped region. The width of the residual first co-doped region is 15 μm, and the width of the residual second co-doped region is 15 μm.

[0135] Example 4 like Figure 13 As shown, a solar cell includes a silicon substrate 10, a first surface 11, a second surface 22, a first doped region 12, a second doped region 13, an isolation region 14, a spacer 15, a first co-doped region 161, a first passivation layer 30, a second passivation layer 40, a first antireflection layer 50, a second antireflection layer 60, a first electrode 71, and a second electrode 72. As shown in the figure, the method for fabricating a solar cell in this embodiment includes the following steps:

[0136] 1. Select a P-doped N-type silicon wafer with a resistivity of 1.5 Ω cm and a thickness of 150 μm; use acid and alkali chemicals to remove organic contaminants and metallic impurities from the surface of the silicon wafer, and then etch and polish the surface of the single crystal silicon wafer.

[0137] 2. In a PECVD furnace tube, using N2O as the oxidant, at an oxidation temperature of 600℃ for 10 min, a tunneling oxide layer with a thickness of 1.5 nm is deposited on the first surface of the silicon substrate; using SiH4 as the reaction gas and Ar as the dilution gas, at a deposition temperature of 600℃ for 90 min, a polycrystalline silicon layer with a thickness of 250 nm is deposited on the surface of the tunneling oxide layer.

[0138] 3. In the PECVD furnace tube, using PH3, SiH4, N2O, and NH3 as deposition raw materials, the deposition temperature is 600℃ and the time is 50min. A phosphorus-containing silicon oxide layer with a thickness of 50nm is deposited on the polycrystalline silicon layer; a silicon oxide mask layer with a thickness of 100nm is deposited on the phosphorus-containing silicon oxide layer.

[0139] 4. Use a laser to open the silicon wafer. The laser parameters are set to a wavelength of 355 nm and an energy density of 0.5 J / cm². Then clean it in a cleaning machine by acid washing. After cleaning, dry it to expose the polycrystalline silicon layer on the back of the silicon wafer.

[0140] 5. The silicon wafer is placed in a boron-doped tube for doping at a temperature of 800℃ for 100 minutes. The boron doping source is BBr3. This forms a polycrystalline silicon region of the first conductivity type, also known as the first doped region, on the first surface of the silicon wafer. Simultaneously, the phosphorus-containing silicon oxide layer on the back side can serve as both a doping source for a second conductivity type impurity region, forming a second conductivity type impurity polycrystalline silicon region, and a boron doping barrier layer. During boron diffusion, the doping source of the second conductivity type impurity region diffuses into the polycrystalline silicon, forming the second doped region. The interdiffusion region between the first and second doped regions, representing the two conductivity types of impurities, forms an isolation region.

[0141] 6. The isolation region is patterned using a laser with a wavelength of 355 nm and an energy density of 2.5 J / cm². The region is then subjected to acid washing, alkali washing, water washing, and drying in a cleaning machine to form localized co-doped regions and spacers. The scanning path of the laser beam is controlled to deviate from the center of the initial isolation region and move closer to the second doped region. This allows the laser and etching solution to completely remove the material from the middle portion of the isolation region, forming spacers. Meanwhile, on the side of the first and second doped regions, some material from the initial isolation region is retained, forming the first and second co-doped regions. The width of the remaining first co-doped region is 15 μm, and the width of the remaining second co-doped region is 8 μm.

[0142] 7. Use a 1.3% NaOH solution for etching for 500 seconds to create a textured surface on the second surface of the silicon wafer and an isolation textured surface on the spacer portion of the first surface (not shown in the figure).

[0143] 8. Immerse the silicon wafer in 25% HF for 600 seconds to remove the phosphorus-containing silicon oxide layer, boron-containing silicon oxide layer, and mask layer; then perform RCA standard cleaning on the silicon wafer to remove surface contaminants.

[0144] 9. Using ALD atomic layer deposition with TMA as the precursor, a dense Al2O3 passivation layer with a thickness of 10nm is deposited on the first and second surfaces of the silicon wafer at a reaction temperature controlled at 300℃. Then, 100nm SiO2 antireflection layers are deposited on the front and back sides of the silicon wafer using PECVD. The passivation layer and the antireflection layer form a dielectric layer.

[0145] Comparative Example 1 like Figure 14 As shown, a solar cell includes a silicon substrate 10, a first surface 11, a second surface 22, a first doped region 12, a second doped region 13, a spacer 15, a first passivation layer 30, a second passivation layer 40, a first antireflection layer 50, a second antireflection layer 60, a first electrode 71, and a second electrode 72. The method is carried out in accordance with Example 1, except that in step 6, the scanning path of the laser beam is controlled to follow the center line of the initial isolation region. However, by optimizing the laser energy density and etching formula, the initial isolation region between the first doped region and the second doped region is completely removed, forming a clean intrinsic spacer without any doped material residue.

[0146] Table 1 shows the relevant parameters of the solar cells corresponding to different embodiments and comparative examples of this application.

[0147] All embodiments (1-4) outperform Comparative Example 1 (conventional process) in all aspects. The embodiments effectively reduce edge recombination in the battery doped region and improve battery conversion efficiency by actively engineering the co-doped region into a functionalized buffer layer, transforming it from a recombination source.

[0148] Example 1: In this example, the first doped region is P-type doped, and the first co-doped region is in contact with the first doped region, which is the optimized doped region on the P side. The Voc is significantly improved, indicating that the P-side passivation optimization contributes significantly to the open circuit voltage, and its effect on suppressing boron-related recombination and improving voltage is outstanding.

[0149] Example 2: In this example, the second doped region is N-type doped, and the second co-doped region is in contact with the second doped region, which is the doped region on the optimized N side. The FF is significantly improved, indicating that it contributes more to improving electron collection and reducing series resistance.

[0150] Example 3: In this example, the first doped region is P-type doped, and the second doped region is N-type doped. The first co-doped region is in contact with the first doped region, and the second co-doped region is in contact with the second doped region. The widths of the first and second co-doped regions are the same, meaning that both the P-side and N-side doped regions are optimized simultaneously. This surpasses any single-sided optimization scheme in terms of Voc, FF, and efficiency, achieving a more balanced and comprehensive improvement. The dual-sided symmetrical design provides more robust and superior overall performance, making it the preferred solution for mass production with high consistency.

[0151] Example 4: In this example, the first doped region is P-type doped and the second doped region is N-type doped. The first co-doped region is in contact with the first doped region, and the second co-doped region is in contact with the second doped region. The widths of the first and second co-doped regions are different, with the width of the first co-doped region being slightly larger than that of the second co-doped region. The concentration change on the P-side is gradual, emphasizing passivation; the concentration change on the N-side is steep, emphasizing conductivity. The highest values ​​are achieved in Voc, FF, Eta, and Rsh, which is superior to symmetrical designs.

[0152] Comparative Example 1: The electrical performance of this scheme is improved. Although this structure achieves electrical isolation, it forms an abrupt junction from the P-type semiconductor to the intrinsic region and then to the N-type semiconductor. This leads to extremely high carrier recombination in the edge region of the doped region, resulting in Voc loss and a significant carrier transport barrier, which in turn leads to the deterioration of FF and series resistance Rs.

[0153] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0154] Although alternative embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make further changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the alternative embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0155] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used merely to distinguish one entity from another, and do not necessarily require or imply any such actual relationship or order between these entities. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or terminal device that includes that element.

[0156] The technical solution provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the principle and implementation of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A solar cell, characterized in that, include: A silicon substrate having a first surface and a second surface disposed opposite to each other, the first surface having an alternately disposed first doped region and a second doped region, the first doped region and the second doped region having different conductivity types, and an isolation region being provided between the first doped region and the second doped region; The isolation region includes at least one spacer portion and a co-doped region located between the spacer portion and the first doped region and / or the second doped region; The co-doped region includes at least a first doping element of a first conductivity type and a second doping element of a second conductivity type. Within the co-doped region, the doping concentration of the first doping element gradually decreases and the doping concentration of the second doping element gradually increases in the direction from the first doping region to the second doping region.

2. The solar cell according to claim 1, characterized in that, The co-doped region includes a first co-doped region and / or a second co-doped region.

3. The solar cell according to claim 2, characterized in that, The first co-doped region and the first doped region are adjacent, and the second co-doped region and the second doped region are adjacent.

4. The solar cell according to claim 2, characterized in that, The first co-doped region is in physical contact with the first doped region, and the second co-doped region is in physical contact with the second doped region.

5. The solar cell according to claim 2, characterized in that, The first co-doped region and / or the second co-doped region include one or more combinations of point-like, block-like, or discrete morphologies.

6. The solar cell according to claim 2, characterized in that, The co-doped region has at least one of the same monocrystalline silicon, amorphous silicon, microcrystalline silicon, or polycrystalline silicon as the first doped region and / or the second doped region.

7. The solar cell according to claim 2, characterized in that, The width of the first co-doped region and / or the second co-doped region in the first direction is 1 μm to 40 μm.

8. The solar cell according to claim 2, characterized in that, The first conductivity type is P-type, the first doping element includes at least one element from group II IA, the second conductivity type is N-type, and the second doping element includes at least one element from group VA; or the first conductivity type is N-type, the first doping element includes at least one element from group VA, the second conductivity type is P-type, and the second doping element includes at least one element from group II IA.

9. The solar cell according to claim 8, characterized in that, In the first co-doped region, the average doping concentration of the first doped element is higher than the doping concentration of the second doped element, and / or, in the second co-doped region, the average doping concentration of the second doped element is greater than the doping concentration of the first doped element.

10. The solar cell according to claim 9, characterized in that, Within the first co-doped region, the net doping concentration of the first doping element gradually decreases in the direction from the first doping region to the second doping region, and / or, within the second co-doped region, the net doping concentration of the second doping element gradually decreases in the direction from the second doping region to the first doping region.

11. The solar cell according to claim 9, characterized in that, Within the first co-doped region, the peak concentration of the first dopant element is 1×10⁻⁶. 19 cm -3 -5×10 21 cm -3 The peak concentration of the second dopant element is 1×10⁻⁶. 17 cm -3 -1×10 19 cm -3 And / or, within the second co-doped region, the peak concentration of the first dopant element is 1 × 10⁻⁶. 18 cm -3 -5×10 19 cm -3 The peak concentration of the second dopant element is 5 × 10⁻⁶. 19 cm -3 -5×10 20 cm -3 .

12. The solar cell according to claim 1, characterized in that, The spacer portion includes one of a velvety surface, a micro-velvety surface, or a planar structure.

13. The solar cell according to claim 1, characterized in that, The width of the spacer in the first direction is 20 μm to 400 μm.

14. The solar cell according to claim 1, characterized in that, The spacer portion is a groove that is recessed from the first surface toward the inside of the silicon substrate.

15. The solar cell according to claim 14, characterized in that, The depth of the spacer is not less than the thickness of the first doped region and / or the second doped region.

16. A method for preparing a solar cell, characterized in that, The preparation method is used to prepare the solar cell according to any one of claims 1-15, and includes the following steps: A silicon substrate is provided, wherein a first doping element of a first conductivity type and a second doping element of a second conductivity type are introduced on a first surface of the silicon substrate; A first doped region and a second doped region are formed in an alternating pattern on a first surface, and an isolation region is formed between adjacent first doped regions and second doped regions. The isolation region is subjected to laser and wet processing to form a first co-doped region comprising at least one spacer portion, a first co-doped region located between the spacer portion and the first doped region, and / or a second co-doped region located between the spacer portion and the second doped region.

17. A photovoltaic module, characterized in that, The photovoltaic module includes the solar cell according to any one of claims 1-15.

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