Solar cell and solar cell module

Abstract

This disclosure relates to the field of solar cell technology, and discloses a solar cell and a solar cell module. The solar cell includes a substrate layer, a first doped semiconductor layer, and a second doped semiconductor layer; the substrate layer includes a first surface and a second surface; the first doped semiconductor layer is formed on the first surface; the second doped semiconductor layer is formed on the second surface; at least one of the first and second doped semiconductor layers is formed as a composite structure layer, the composite structure layer including alternately arranged contact regions and non-contact regions, a first structural surface with a first textured structure is formed on the side of the contact region relatively away from the substrate layer, and a second structural surface with a second textured structure is formed on the side of the non-contact region relatively away from the substrate layer, the density of the first textured structure being greater than the density of the second textured structure. This disclosure balances the light-trapping performance and passivation quality of the solar cell.

Description

Technical Field

[0001] This disclosure relates to the field of solar cell technology, and more specifically, to a solar cell and a solar cell module. Background Technology

[0002] The photoelectric conversion efficiency of solar cells mainly depends on the effective utilization of incident light and the effective collection of photogenerated carriers. To extend the optical path of incident light inside the solar cell, related technologies use alkaline solutions to etch the silicon wafer surface, obtaining a textured structure. This textured structure can increase the light absorption path through multiple reflections and refractions, which is one of the key means to improve short-circuit current. However, with the continuous development of photovoltaic technology, especially the gradual application of various cell structures such as tunneling oxide passivated contacts, back contacts, heterojunctions, and perovskite / crystalline silicon tandem solar cells, the traditional single textured morphology design can no longer meet all performance requirements, and its limitations are gradually being exposed.

[0003] Specifically, when the textured surface exhibits a "large and sparse" morphology, its surface undulations are gentler and the peak-to-valley spacing is larger, which is beneficial for the subsequent deposition of a uniform and dense passivation and antireflection film layer. This effectively reduces the interface defect state density and achieves excellent surface passivation. However, this "large and sparse" structure has relatively weak scattering and trapping capabilities for incident light, limiting the effective transmission of light within the battery and hindering the full excitation and collection of photogenerated carriers. Furthermore, in the screen-printed electrode process, this structure has fewer contact points with the metal paste, which can easily lead to increased contact resistance and affect the fill factor.

[0004] Conversely, when the textured surface exhibits a "small and dense" morphology, its surface possesses abundant peaks and valleys, enabling multiple reflections and refractions of incident light, significantly enhancing the light-trapping effect and improving short-circuit current. However, this sharp peak-valley structure can easily lead to uneven film growth at the peaks during subsequent passivation film deposition, resulting in problems such as micropores, structural defects, or poor coverage. It may also induce local leakage channels, causing a decrease in open-circuit voltage and fill factor, thereby limiting the improvement of battery efficiency. Summary of the Invention

[0005] This disclosure provides a solar cell and a solar cell module to solve the problem that existing cell surfaces are difficult to balance light trapping performance and passivation quality.

[0006] In a first aspect, this disclosure provides a solar cell, which includes a substrate layer, a first doped semiconductor layer, and a second doped semiconductor layer; the substrate layer includes a first surface and a second surface disposed opposite to each other; the first doped semiconductor layer is formed on the first surface; the second doped semiconductor layer is formed on the second surface, and the doping types of the first doped semiconductor layer and the second doped semiconductor layer are opposite; at least one of the first doped semiconductor layer and the second doped semiconductor layer is formed as a composite structure layer, the composite structure layer includes alternately arranged contact areas and non-contact areas, the surface of the contact area protrudes relative to the surface of the non-contact area, a first structural surface with a first textured structure is formed on the side of the contact area that is relatively far from the substrate layer, and a second structural surface with a second textured structure is formed on the side of the non-contact area that is relatively far from the substrate layer, the density of the first textured structure is greater than the density of the second textured structure, and electrodes are disposed on at least a portion of the contact area.

[0007] Beneficial Effects: This disclosure forms a composite structure layer by shaping the first doped semiconductor layer and / or the second doped semiconductor layer. The first structural surface is formed by the contact area of ​​the composite structure, and the second structural surface is formed by the non-contact area. This allows for the construction of structural surfaces with different morphologies in different regions of the same surface of the battery. The first structural surface has a first texture structure, and the second structural surface has a second texture structure. By configuring the density of the first texture structure to be greater than that of the second texture structure, a significant difference is created between the structural densities on the first and second structural surfaces. The denser first texture structure in the contact area, which is in contact with the electrode, helps increase the effective contact area with the electrode paste, forming a good ohmic contact, which facilitates the transport of photogenerated carriers and reduces resistivity. The sparser second texture structure in the non-contact area, which is not in contact with the electrode, is conducive to the deposition of a uniform and dense passivation and antireflection film layer, thereby reducing the recombination rate of photogenerated carriers and improving surface passivation performance. Furthermore, both the first and second texture structures are uneven surface morphologies, which can effectively increase the number of reflections and refractions of incident light, exhibiting good light-trapping ability. In particular, the denser first texture structure has superior light-trapping performance.

[0008] In some optional implementations, the density of the first texture structure ranges from 1E5 to 9E5 units / mm. 2 ; and / or, the density of the second texture structure ranges from 0.1E5 to 6E5 particles / mm. 2 And / or, the difference between the density of the first texture structure and the density of the second texture structure is greater than or equal to 2E3 particles / mm. 2 In some alternative embodiments, the density of the first texture structure ranges from 1E3 to 3E4 units / mm. 2 ; and / or, the density of the second texture structure ranges from 5E2 to 2E4 per mm. 2; and / or, the difference between the density of the first texture structure and the density of the second texture structure is greater than or equal to 2E2 particles / mm. 2 .

[0009] Beneficial effects: When the density of the first textured structure is within the above-mentioned density range, it can ensure that the electrode paste and the first structure surface form a good ohmic contact; when the density of the second textured structure is within the above-mentioned density range, it can ensure that the subsequent passivation film layer is uniformly deposited on the second structure surface.

[0010] In some alternative implementations, the height difference between the first structural surface and the second structural surface ranges from 0.5 to 4 μm.

[0011] Beneficial effects: The height difference can be formed based on the difference in doping concentration between the contact area and the non-contact area. If the height difference is less than 0.5 μm, it indicates that the difference in doping concentration between the contact area and the non-contact area is small and the barrier difference is not obvious, which leads to an increase in the carrier recombination rate and a decrease in open-circuit voltage and short-circuit current. If the height difference is greater than 4 μm, it indicates that the substrate layer at the non-contact area is over-etched, introducing more surface defects and causing a decrease in open-circuit voltage. Therefore, ensuring that the height difference between the first structural plane and the second structural plane is within the above range can effectively reduce the interfacial recombination and parasitic absorption of the battery and improve the photoelectric conversion efficiency of the battery.

[0012] In some alternative implementations, the doping concentration in the contact region is greater than that in the non-contact region.

[0013] Beneficial effects: This disclosure sets the doping concentration in the contact region to be greater than that in the non-contact region. On the one hand, the higher doping concentration in the contact region ensures that the electrodes placed on the contact region form a good ohmic contact, thereby improving carrier collection and transport performance. On the other hand, the lower doping concentration in the non-contact region helps to reduce parasitic absorption at the interface of the non-contact region, improving photoelectric conversion efficiency. In addition, the lower doping concentration in the non-contact region also helps to form a second textured structure with a lower density in the non-contact region.

[0014] In some alternative implementations, the doping concentration of the contact region ranges from 2E18 to 1E21 atoms / cm². 3 ; and / or, the doping concentration in the non-contact region is less than 1E18 atoms / cm². 3 .

[0015] Beneficial effects: This disclosure limits the doping concentration range of the contact area and the non-contact area to the above range, ensuring that the contact area and the non-contact area form a doping concentration difference. On the one hand, it avoids that the doping concentration difference is too large, which would lead to an excessive difference in the morphology of the first structural surface and the second structural surface and affect the deposition quality of the passivation film. On the other hand, it avoids that the doping concentration difference is too small, which would not have an obvious effect on different areas. Limiting it to the above range helps to comprehensively improve the optical and electrical performance of the battery.

[0016] In some optional embodiments, the solar cell further includes a first passivation antireflection layer and a second passivation antireflection layer, wherein the first passivation antireflection layer is formed on a first doped semiconductor layer and the second passivation antireflection layer is formed on a second doped semiconductor layer; the electrode includes a first electrode and a second electrode, wherein the first electrode is configured to be disposed on the first passivation antireflection layer and connected to the first doped semiconductor layer, and the second electrode is configured to be disposed on the second passivation antireflection layer and connected to the second doped semiconductor layer.

[0017] Beneficial Effects: This disclosure forms a first passivation and antireflection layer on a first doped semiconductor layer and a second passivation and antireflection layer on a second doped semiconductor layer. The first and second passivation and antireflection layers passivate and reduce reflection on the first and second surfaces of the solar cell, reducing recombination losses of photogenerated carriers, increasing open-circuit voltage and fill factor, coupling more sunlight into the substrate layer, increasing light absorption, and improving the photoelectric conversion efficiency of the cell. This disclosure also connects the first electrode to the first doped semiconductor layer and the second electrode to the second doped semiconductor layer, thereby allowing electrons and holes to be output through the first and second electrodes respectively, achieving efficient photoelectric conversion. Furthermore, this disclosure shapes the first and / or second doped semiconductor layers into a composite structure layer. By combining the different structural planes of the composite structure layer with the first and / or second passivation and antireflection layers, the resistivity is reduced while the passivation performance of the cell is improved.

[0018] In some alternative embodiments, one of the first doped semiconductor layer and the second doped semiconductor layer includes an emitter layer, and the other includes a conductive passivation layer; or, at least one of the first doped semiconductor layer and the second doped semiconductor layer includes a conductive passivation layer.

[0019] In some alternative embodiments, a tunneling layer is provided between the conductive passivation layer and the substrate layer.

[0020] In some optional embodiments, both the first texture structure and the second texture structure include a pyramidal structure; or, the first texture structure includes a non-pyramidal structure and the second texture structure includes a pyramidal structure; or, both the first texture structure and the second texture structure include a non-pyramidal structure. In some optional embodiments, the density of the first texture structure ranges from 1E3 to 3E4 particles / mm. 2 ; and / or, the density of the second texture structure ranges from 5E2 to 2E4 per mm. 2 ; and / or, the difference between the density of the first texture structure and the density of the second texture structure is greater than or equal to 2E2 particles / mm. 2 .

[0021] Secondly, this disclosure also provides a solar cell module comprising the aforementioned solar cell. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the specific embodiments of this disclosure or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 A schematic diagram of the structure of a solar cell in an embodiment of this disclosure is shown; Figure 2 The following are side electron microscope images of the first and second structural surfaces in an embodiment of this disclosure; Figure 3 A side electron microscope image of the first structural surface in an embodiment of this disclosure is shown; Figure 4 A side electron microscope image of the second structural surface in an embodiment of this disclosure is shown; Figure 5 A top electron microscope image of the first structural surface in an embodiment of this disclosure is shown; Figure 6 A top electron microscope image of the second structural surface in an embodiment of this disclosure is shown.

[0024] Explanation of reference numerals in the attached figures: 1. Basal layer; 2. First doped semiconductor layer; 21. Contact region; 211. First structural surface; 211a. First textured structure; 22. Non-contact region; 221. Second structural surface; 221a. Second textured structure; 3. Second doped semiconductor layer; 31. Tunneling layer; 32. Doped layer; 4. First passivation anti-reflection layer; 5. Second passivation anti-reflection layer; 6. Electrode; 61. First electrode; 62. Second electrode. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0026] refer to Figures 1 to 6 This disclosure provides a solar cell, which includes a substrate layer 1, a first doped semiconductor layer 2, and a second doped semiconductor layer 3. The substrate layer 1 includes a first surface and a second surface disposed opposite to each other. The first doped semiconductor layer 2 is formed on the first surface. The second doped semiconductor layer 3 is formed on the second surface, and the doping types of the first doped semiconductor layer 2 and the second doped semiconductor layer 3 are opposite. At least one of the first doped semiconductor layer 2 and the second doped semiconductor layer 3 is formed as a composite structure layer. For example, the first doped semiconductor layer 2 is formed as a composite structure layer, which includes alternately arranged contact regions 21 and non-contact regions 22. The surface of the contact region 21 protrudes relative to the surface of the non-contact region 22. A first structural surface 211 with a first textured structure 211a is formed on the side of the contact region 21 that is away from the substrate layer 1, and a second structural surface 221 with a second textured structure 221a is formed on the side of the non-contact region 22 that is away from the substrate layer 1. The density of the first textured structure 211a is greater than the density of the second textured structure 221a. An electrode 6 is suitable for being disposed on the first structural surface 211 of the contact region 21. It is understandable that the second doped semiconductor layer 3 can also be formed as a composite structure layer. The structure of the composite structure layer is basically the same as that of the first doped semiconductor layer 2, also including alternating contact areas and non-contact areas. The surface of the contact area protrudes relatively from the surface of the non-contact area. The side of the contact area that is relatively far from the substrate layer forms a first structural surface with a first texture structure, and the side of the non-contact area that is relatively far from the substrate layer forms a second structural surface with a second texture structure. The density of the first texture structure is greater than the density of the second texture structure. Electrodes are suitable for being disposed on the first structural surface of the contact area. For example, the second doped semiconductor layer 3 can form a polysilicon finger structure.

[0027] In the aforementioned first doped semiconductor layer 2 and second doped semiconductor layer 3, one is configured as a P-type doped layer and the other as an N-type doped layer, thereby forming a built-in electric field within the substrate layer 1. When sunlight shines on it, this electric field can separate the generated electron-hole pairs, thereby forming photogenerated carriers. Furthermore, the first doped semiconductor layer 2 and the second doped semiconductor layer 3 are respectively doped with boron or phosphorus to improve the conductivity of the substrate layer 1, thereby increasing the concentration and mobility of photogenerated carriers, reducing recombination losses, and thus improving the photoelectric conversion efficiency of the battery. In this disclosure, the first doped semiconductor layer 2 and / or the second doped semiconductor layer 3 are formed into a composite structure layer. The contact region 21 in the composite structure forms a first structural surface 211, and the non-contact region 22 forms a second structural surface 221, thereby constructing structural surfaces with different morphologies in different areas of the same surface of the battery. The first structural surface 211 has a first texture structure 211a, and the second structural surface 221 has a second texture structure 221a. By configuring the density of the first texture structure 211a to be greater than that of the second texture structure 221a, a significant difference is created between the structure density on the first structure surface 211 and the structure density on the second structure surface 221. This results in a denser first texture structure 211a forming in the contact area 21 that contacts the electrode 6, which helps increase the effective contact area with the electrode paste, forming a good ohmic contact, facilitating the transport of photogenerated carriers, and reducing resistivity. Conversely, a sparser second texture structure 221a forms in the non-contact area 22 that does not contact the electrode 6, which is beneficial for depositing a uniform and dense passivation and antireflection film layer, thereby reducing the recombination rate of photogenerated carriers and improving surface passivation performance. Furthermore, since both the first texture structure 211a and the second texture structure 221a are uneven surface morphologies, they can effectively increase the number of reflections and refractions of incident light, exhibiting good light-trapping ability. In particular, the denser first texture structure 211a has even better light-trapping performance.

[0028] The aforementioned composite structure layer can be understood as a surface structure layer after local structural differentiation design of the first doped semiconductor layer 2 and / or the second doped semiconductor layer 3. The first doped semiconductor layer 2 and the second doped semiconductor layer 3 can be a stacked passivation contact film layer of the emitter layer, tunneling layer 31, and conductive passivation layer (such as a doped polycrystalline silicon layer) on the light-receiving or back-light-receiving surface in a TOPCon cell; or a stacked passivation contact film layer of intrinsic amorphous silicon layers and amorphous silicon layers with different polarities located on both sides of the substrate layer 1 in a heterojunction cell; or other types of passivation contact film layers. Based on this, at least one of the first doped semiconductor layer 2 and the second doped semiconductor layer 3 is configured as a composite structure layer with localized differentiation design. In some embodiments, it can be understood that the non-contact region 22 of the first doped semiconductor layer 2 or the second doped semiconductor layer 3 does not include the emitter layer or the passivation contact film layer; therefore, the non-contact region 22 of the first doped semiconductor layer 2 or the second doped semiconductor layer 3 includes a portion of the substrate layer 1.

[0029] In summary, one of the first doped semiconductor layer 2 and the second doped semiconductor layer 3 includes an emitter layer, and the other includes a conductive passivation layer; or, at least one of the first doped semiconductor layer 2 and the second doped semiconductor layer 3 includes a conductive passivation layer. Specifically, one of the first doped semiconductor layer 2 and the second doped semiconductor layer 3 is P-type, and the other is N-type. In some embodiments, a tunneling layer 31 is disposed between the conductive passivation layer and the substrate layer 1.

[0030] like Figure 1 As shown, this disclosure uses the example of a first doped semiconductor layer 2 on the light-receiving surface being formed into a composite structure layer, and a second doped semiconductor layer 3 on the backlighting surface being formed into a conventional passivated contact structure. The first doped semiconductor layer 2 is configured as a P-type doped layer, such as the P-type emitter layer in a TOPCon battery, and the second doped semiconductor layer 3 is configured as an N-type doped layer, such as an N-type passivated contact structure including a tunneling layer 31 and a doped polysilicon layer. This differentiated design of local areas on the light-receiving surface helps to improve the electrical and optical performance of the light-receiving surface, thereby effectively improving the photoelectric conversion efficiency of the battery.

[0031] In some embodiments, the doping concentration of the contact region 21 is greater than the doping concentration of the non-contact region 22. This disclosure sets the doping concentration of the contact region 21 higher than that of the non-contact region 22. On the one hand, the higher doping concentration of the contact region 21 ensures good metal contact between the electrode 6 and the contact region 21, thereby improving carrier collection and transport performance. On the other hand, the lower doping concentration of the non-contact region 22 helps reduce parasitic absorption at the interface of the non-contact region 22, improving photoelectric conversion efficiency. Furthermore, the lower doping concentration of the non-contact region 22 also helps to form a lower density second textured structure 221a in the non-contact region 22.

[0032] Specifically, the doping concentration of contact region 21 ranges from 2E18 to 1E21 atoms / cm². 3 For example, 5E18 atoms / cm 3 1E19 atoms / cm 3 1E20 atoms / cm 3 1E21 atoms / cm 3 etc.; and / or, the doping concentration range of the non-contact region 22 is less than 1E18 atoms / cm². 3 For example, 1E16 atoms / cm 3 1E17 atoms / cm 3The present disclosure limits the doping concentration range of the contact region 21 and the non-contact region 22 to the above range, ensuring that the contact region 21 and the non-contact region 22 form a doping concentration difference. On the one hand, it avoids that the doping concentration difference is too large, which would lead to an excessive difference in the morphology of the first structural surface 211 and the second structural surface 221 and affect the deposition quality of the passivation film. On the other hand, it avoids that the doping concentration difference is too small, which would not have an obvious effect on different densities. Limiting it to the above range helps to comprehensively improve the optical and electrical performance of the battery.

[0033] In some embodiments, the first texture structure 211a and the second texture structure 221a can be one or more of a pyramid structure and a non-pyramid structure. When the first texture structure 211a is a pyramid structure, its density ranges from 1E5 to 9E5 particles / mm. 2 When the first texture structure 211a is a non-pyramid structure, its density ranges from 1E3 to 3E4 particles / mm. 2 ; and / or, when the second texture structure 221a is a pyramid structure, its density ranges from 0.1E5 to 6E5 particles / mm. 2 When the second texture structure 221a is a non-pyramid structure, its density ranges from 5E2 to 2E4 particles / mm. 2 When the density of the first textured structure 211a is within the aforementioned density range, good ohmic contact between the electrode paste and the first structure surface 211 can be ensured; when the density of the second textured structure 221a is within the aforementioned density range, uniform deposition of the subsequent passivation film layer on the second structure surface 221 can be ensured. In some embodiments, such as Figure 5 and Figure 6 As shown, the first texture structure 211a and the second texture structure 221a are pyramid structures. In some embodiments, the first texture structure 211a is a non-pyramid structure and the second texture structure 221a is a pyramid structure. In still other embodiments, both the first texture structure 211a and the second texture structure 221a are non-pyramid structures. The aforementioned non-pyramid structure can be a base structure, which is a concave or convex structure, and its top or bottom surface is polygonal.

[0034] In some embodiments, when both the first texture structure 211a and the second texture structure 221a are pyramid structures, the difference between the density of the first texture structure 211a and the density of the second texture structure 221a is greater than or equal to 2E3 particles / mm. 2 For example, it can be 5E3 pieces / mm 2 8E3 pieces / mm 2 2E4 pieces / mm 2 1E5 pieces / mm 2In other embodiments, when both the first texture structure 211a and the second texture structure 221a are non-pyramid structures, the difference between the density of the first texture structure 211a and the density of the second texture structure 221a is greater than or equal to 2E2 particles / mm. 2 For example, it can be 4E2 pieces / mm 2 8E2 pieces / mm 2 2E3 pieces / mm 2 8E3 pieces / mm 2 wait.

[0035] In some embodiments, the height of the pyramid structure is less than or equal to 4 μm, for example, it can be 0.5 μm, 1 μm, 2 μm, 3 μm, etc., and the dimensions (length or width) of the base of the pyramid structure are less than or equal to 5 μm, for example, it can be 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, etc. In some embodiments, the height or depth of the base structure is less than or equal to 2 μm, for example, it can be 0.2 μm, 0.5 μm, 1 μm, 1.5 μm, etc. The dimensions (length or width) of the bottom or top surface of the base structure are less than or equal to 80 μm, for example, it can be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, etc.

[0036] In some embodiments, the average size, height, or depth of the first texture structure 211a is smaller than the average size, height, or depth of the second texture structure 221a.

[0037] like Figure 1 , Figure 3 and Figure 4 As shown, the height difference h between the first structural surface 211 and the second structural surface 221 ranges from 0.5 μm to 4 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, etc. The height difference can be formed based on the difference in doping concentration between the contact region 21 and the non-contact region 22. If the height difference is less than 0.5 μm, it indicates that the difference in doping concentration between the contact region 21 and the non-contact region 22 is small, and the barrier difference is not obvious, which leads to an increase in the carrier recombination rate and a decrease in the open-circuit voltage and short-circuit current. If the height difference is greater than 4 μm, it indicates that the substrate layer 1 at the non-contact region 22 is over-etched, introducing more surface defects, which leads to a decrease in the open-circuit voltage. Therefore, ensuring that the height difference between the first structural surface 211 and the second structural surface 221 is within the above range can effectively reduce the interfacial recombination and parasitic absorption of the battery and improve the photoelectric conversion efficiency of the battery.

[0038] In some embodiments, the solar cell further includes a first passivation antireflection layer 4 and a second passivation antireflection layer 5, wherein the first passivation antireflection layer 4 is formed on a first doped semiconductor layer 2 and the second passivation antireflection layer 5 is formed on a second doped semiconductor layer 3; the electrode 6 includes a first electrode 61 and a second electrode 62, wherein the first electrode 61 is configured to be disposed on the first passivation antireflection layer 4 and connected to the first doped semiconductor layer 2, and the second electrode 62 is configured to be disposed on the second passivation antireflection layer 5 and connected to the second doped semiconductor layer 3.

[0039] This disclosure forms a first passivation and antireflection layer 4 on a first doped semiconductor layer and a second passivation and antireflection layer 5 on a second doped semiconductor layer 3. The first passivation and antireflection layer 4 and the second passivation and antireflection layer 5 passivate and reduce reflection on the first and second surfaces of the solar cell, reducing recombination losses of photogenerated carriers, increasing open-circuit voltage and fill factor, coupling more sunlight into the substrate layer 1, increasing light absorption, and improving the photoelectric conversion efficiency of the cell. This disclosure also connects a first electrode 61 to the first doped semiconductor layer 2 and a second electrode 62 to the second doped semiconductor layer 3, thereby outputting electrons and holes through the first electrode 61 and the second electrode 62 respectively, achieving efficient photoelectric conversion. Furthermore, this disclosure forms the first doped semiconductor layer 2 and / or the second doped semiconductor layer 3 into a composite structure layer, utilizing the different structural planes of the composite structure layer in combination with the first passivation and antireflection layer 4 and / or the second passivation and antireflection layer 5 to reduce resistivity while improving the passivation performance of the cell. In some embodiments, the thickness of the first passivation and antireflection layer 4 or the second passivation and antireflection layer 5 is 50~150 nm.

[0040] refer to Figures 1 to 6 This disclosure also provides a method for fabricating a solar cell, which is used to fabricate the above-mentioned solar cell. Taking a solar cell in which the first doped semiconductor layer 2 is formed into a composite structure layer and the second doped semiconductor layer 3 is formed into a conventional passivated contact structure as an example, the fabrication method specifically includes the following steps: S100, a base layer 1 is provided, the base layer 1 including a first surface and a second surface disposed opposite to each other.

[0041] For example, an N-type silicon wafer can be selected as the substrate layer 1, wherein the first surface is the light-receiving surface of the N-type silicon wafer and the second surface is the backlight surface of the N-type silicon wafer.

[0042] S200, a first doped semiconductor layer 2 is formed on the first surface of the substrate layer 1.

[0043] S300, a second doped semiconductor layer 3 is formed on the second surface of the substrate layer 1.

[0044] The first doped semiconductor layer 2 and the second doped semiconductor layer 3 have opposite doping types. At least one of the first doped semiconductor layer 2 and the second doped semiconductor layer 3 is formed as a composite structure layer. The composite structure layer includes alternately arranged contact regions 21 and non-contact regions 22. The surfaces of the contact regions 21 protrude relative to each other. A first structural surface 211 with a first textured structure 211a is formed on the side of the contact region 21 that is away from the substrate layer 1. A second structural surface 221 with a second textured structure 221a is formed on the side of the non-contact region 22 that is away from the substrate layer 1. The density of the first textured structure 211a is greater than the density of the second textured structure 221a. Exemplarily, the first doped semiconductor layer 2 is formed as a composite structure layer, and the second doped semiconductor layer 3 is formed as a passivated contact structure.

[0045] S400, an electrode 6 is formed on the contact area 21.

[0046] In actual fabrication, after the second texture structure 221a is formed in step S300 and before the electrode 6 is formed in step S400, the process further includes: forming a first passivation antireflection layer 4 on the first surface and forming a second passivation antireflection layer 5 on the second surface.

[0047] For example, silver paste is printed on the first passivation antireflection layer 4 and the second passivation antireflection layer 5 respectively. After sintering, the silver paste forms the first electrode 61 and the second electrode 62 of the electrode 6. The first electrode 61 passes through the first passivation antireflection layer 4 and is connected to the contact area 21. The second electrode 62 passes through the second passivation antireflection layer 5 and is connected to the doped layer 32. The polarity of the second electrode 62 is opposite to that of the first electrode 61.

[0048] This disclosure involves forming a first doped semiconductor layer 2 and a second doped semiconductor layer 3 on the first and second surfaces of a substrate layer 1, respectively. At least one of the first doped semiconductor layer 2 and the second doped semiconductor layer 3 is formed as a composite structure layer. The contact region 21 and the non-contact region 22 in the composite structure form a first structural surface 211 and a second structural surface 221 with different textures, thereby constructing structural surfaces with different morphologies to suit their respective process requirements. On one hand, the denser first texture structure 211a in the first structural surface 211 increases the effective contact area with the electrode paste, improving the transport rate of photogenerated carriers. On the other hand, the sparser second texture structure 221a in the second structural surface 221 improves the film formation quality of the passivation and antireflection film, enhancing the passivation and antireflection effect.

[0049] Specifically, the following explanation is based on the example of the first doped semiconductor layer 2 being formed into a composite structure layer: S201 provides an initial structural layer, which includes a contact area 21 and a non-contact area 22.

[0050] For example, the first surface of an N-type silicon wafer serves as the initial structural layer.

[0051] S202, a first surface treatment is performed on one side surface of the initial structural layer to form a first texture structure 211a in the contact area 21 and the non-contact area 22, and the contact area 21 with the first texture structure 211a forms a first structural surface 211.

[0052] For example, performing a first surface treatment on the entire light-receiving surface of the substrate layer 1 may include forming a first texture structure 211a on one side surface of the initial structural layer using an alkaline solution and a texturing additive, wherein the density of the first texture structure 211a is 2.1E5 pieces / mm. 2 This disclosure employs a mixture of alkaline solution and texturing additive to perform a first surface treatment on one side of the initial structural layer, thereby obtaining a first structural surface 211 with a first texture structure 211a. The processing technology is simple and the density of the first texture structure 211a is easy to control.

[0053] S203, doping treatment is performed on the initial structural layer after the first surface treatment.

[0054] For example, a boron-containing gas can be introduced into a tube diffusion furnace to deposit a first doped semiconductor layer 2 on the light-receiving surface of an N-type silicon wafer, followed by the introduction of oxygen to perform high-temperature treatment on the N-type silicon wafer to repair surface defects.

[0055] S204, the non-contact area 22 of the initial structural layer is subjected to a second surface treatment to form a second texture structure 221a, and the non-contact area 22 with the second texture structure 221a forms a second structural surface 221.

[0056] This disclosure first performs a first surface treatment on the first surface of the substrate layer 1 to form a first textured structure 211a, and then performs a doping treatment on the initial structure layer after the first surface treatment, thereby forming a first structure surface 211 with the first textured structure 211a on the contact area 21 of the substrate layer 1. Finally, an additional second surface treatment is performed on the non-contact area 22, such as using an alkaline solution for the second surface treatment, thereby forming a second structure surface 221 with the second textured structure 221a on the non-contact area 22 of the substrate layer 1. By using multiple surface treatments in different areas, structure surfaces with different morphologies can be formed quickly and effectively, improving the overall performance of the battery and being compatible with existing process steps.

[0057] Specifically, the step of performing a second surface treatment on the non-contact area 22 of the initial structural layer may include the following steps: setting an initial photosensitive shielding layer on the entire surface of the doped initial structural layer; patterning the initial photosensitive shielding layer to form a photosensitive shielding layer that covers the contact area 21 and exposes the non-contact area 22; and performing a second surface treatment on the non-contact area 22 using a wet etching process to form a second structural surface 221 with a second textured structure 221a in the non-contact area 22, wherein the density of the second textured structure 221a is 1.6E5 units / mm. 2 The height difference h between the first structural surface 211 and the second structural surface 221 is 1.9 μm; the photosensitive blocking layer is removed.

[0058] For example, the photosensitive masking layer can be coated with materials such as photosensitive emulsion. The photosensitive masking layer on the contact area 21 is cured by ultraviolet light, and the photosensitive emulsion on the non-contact area 22 is removed, thereby achieving patterning processing. The photosensitive emulsion can be removed by organic solvents or plasma. After removing the photosensitive emulsion, surface polishing is performed to remove the damaged layer and optimize the surface morphology. After removing the photosensitive emulsion, the N-type silicon wafer is thoroughly cleaned to remove organic contaminants and metal ions introduced in each step.

[0059] This disclosure employs a photosensitive shielding layer as a protective film layer to protect the contact area 21 from the second surface treatment. Utilizing the photocurable properties of the photosensitive shielding layer and a wet etching process, it effectively shields the untreated areas, meeting the process requirements for patterning in both the contact area 21 and the non-contact area 22, while also reducing damage to the battery surface structure layer. Specifically, photocuring is performed in the contact area 21 to create a hardness that resists the second surface treatment, while the non-contact area 22 is not photocured, making it suitable for etching by the second surface treatment. Because the photosensitive shielding layer located in the contact area 21 has high hardness, after the second surface treatment is completed, a removal method with a corrosion intensity greater than that of the second surface treatment is used.

[0060] After the first textured structure 211a is formed and before the second textured structure 221a is formed, the second doped semiconductor layer 3 is prepared. The second doped semiconductor layer 3 is formed into a passivated contact structure, which includes the following steps: S301, an initial tunneling layer is formed on the second surface of the base layer 1.

[0061] For example, oxygen is introduced using low-pressure chemical vapor deposition to form an initial tunneling layer on the back surface of an N-type silicon wafer.

[0062] S302, an initial doped layer is formed on the initial tunneling layer, and the initial doped layer and the initial tunneling layer constitute the initial second initial doped semiconductor layer.

[0063] For example, an amorphous silicon layer is deposited on the initial tunneling layer, and then a phosphorus source is introduced to crystallize it into an N-type polycrystalline silicon layer.

[0064] S303, Remove the second doped semiconductor layer 3 from the first surface and side surfaces.

[0065] For example, an acidic solution, such as hydrofluoric acid solution, and an alkaline solution, such as sodium hydroxide solution, are used to remove the second initial doped semiconductor layer on the first surface and the side surface, leaving the second initial doped semiconductor layer on the second surface to form a second doped semiconductor layer 3, which includes a tunneling layer 31 and a doped layer 32.

[0066] For ease of description, the battery obtained by the above preparation method is used as the example battery. Comparative Example 1, Comparative Example 2, and Comparative Example 3 batteries are also selected. The difference between Comparative Example 1 and the example battery is that the density of the first texture structure 211a is 0.8E5 cells / mm². 2 The density of the second texture structure 221a is 1.2E5 particles / mm². 2 The height difference h between the first structural surface 211 and the second structural surface 221 is 1.3 μm. The difference between the battery in Comparative Example 2 and the battery in the embodiment is that the density of the first textured structure 211a is 2.3E5 cells / mm². 2 The density of the second texture structure 221a is 2.8E5 particles / mm². 2 The height difference h between the first structural surface 211 and the second structural surface 221 is 0.7 μm. The difference between the battery in Comparative Example 3 and the battery in the embodiment is that the density of the first textured structure 211a is 1.2E5 cells / mm². 2 The density of the second texture structure 221a is 1.1E5 particles / mm². 2 The height difference h between the first structural surface 211 and the second structural surface 221 is 0.2 μm.

[0067] The densities of the first texture structure 211a and the second texture structure 221a described above can be characterized by three-dimensional morphology of the surfaces of the contact area 21 and the non-contact area 22 using an Olympus microscope. Based on the acquired microscopic images, the texture structures within a unit area (1 mm²) are counted and statistically analyzed using the image analysis software built into the device to measure the texture structure density.

[0068] Based on this, the batteries of the above embodiments, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were subjected to electrical performance tests, and the data shown in the table below were obtained:

[0069] As shown in the table above, the battery in this embodiment outperforms the batteries in Comparative Example 1, Comparative Example 2, and Comparative Example 3 in all current performance parameters, including conversion efficiency (Eta), open-circuit voltage (Uoc), short-circuit current (Isc), and fill factor (FF). This means that the use of the first structural surface 211 and the second structural surface 221 in this embodiment effectively improves the performance of the solar cell, and the height difference between the first structural surface 211 and the second structural surface 221 has a positive effect on battery performance. The first textured structure 211a of the battery in Comparative Example 1 has a lower density, resulting in a smaller effective contact area between the paste and the structural surface during printing. The second textured structure 221a of the battery in Comparative Example 2 has a higher density, making it difficult to deposit a uniform and dense passivation film, ultimately leading to a significant decrease in battery efficiency. In the battery in Comparative Example 3, the height difference h between the contact area 21 and the non-contact area 22 is too small, resulting in an insignificant barrier difference, which increases the surface recombination rate and reduces the open-circuit voltage and short-circuit current.

[0070] This disclosure also provides a solar cell module comprising the solar cells described above.

[0071] Although embodiments of the present disclosure have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present disclosure, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A solar cell, characterized in that, include: A base layer, the base layer including a first surface and a second surface disposed opposite to each other; A first doped semiconductor layer is formed on the first surface; A second doped semiconductor layer is formed on the second surface, wherein the doping types of the first doped semiconductor layer and the second doped semiconductor layer are opposite. In the first doped semiconductor layer and the second doped semiconductor layer, at least one of them is formed as a composite structure layer. The composite structure layer includes alternating contact areas and non-contact areas. The surface of the contact area protrudes relative to the surface of the non-contact area. The side surface of the contact area away from the substrate layer forms a first structural surface with a first texture structure. The side surface of the non-contact area away from the substrate layer forms a second structural surface with a second texture structure. The density of the first texture structure is greater than the density of the second texture structure. Electrodes are disposed on at least a portion of the contact area.

2. The solar cell according to claim 1, characterized in that, The density of the first texture structure ranges from 1E5 to 9E5 per mm. 2 ; and / or, the density of the second texture structure ranges from 0.1E5 to 6E5 particles / mm. 2 ; and / or, the difference between the density of the first texture structure and the density of the second texture structure is greater than or equal to 2E3 particles / mm. 2 .

3. The solar cell according to claim 1, characterized in that, The height difference between the first structural surface and the second structural surface ranges from 0.5 to 4 μm.

4. The solar cell according to any one of claims 1 to 3, characterized in that, The doping concentration in the contact region is greater than that in the non-contact region.

5. The solar cell according to claim 4, characterized in that, The doping concentration of the contact region ranges from 2E18 to 1E21 atoms / cm². 3 ; and / or, the doping concentration range of the non-contact region is less than 1E18 atoms / cm 3 .

6. The solar cell according to claim 5, characterized in that, Also includes: A first passivation anti-reflection layer and a second passivation anti-reflection layer, wherein the first passivation anti-reflection layer is formed on the first doped semiconductor layer and the second passivation anti-reflection layer is formed on the second doped semiconductor layer; The electrode includes a first electrode and a second electrode. The first electrode is configured to be disposed on the first passivation antireflection layer and connected to the first doped semiconductor layer. The second electrode is configured to be disposed on the second passivation antireflection layer and connected to the second doped semiconductor layer.

7. The solar cell according to claim 1, characterized in that, One of the first doped semiconductor layer and the second doped semiconductor layer includes an emitter layer, and the other includes a conductive passivation layer. Alternatively, at least one of the first doped semiconductor layer and the second doped semiconductor layer may include a conductive passivation layer.

8. The solar cell according to claim 7, characterized in that, A tunneling layer is provided between the conductive passivation layer and the substrate layer.

9. The solar cell according to claim 1, characterized in that, Both the first texture structure and the second texture structure include a pyramid-shaped structure; Alternatively, the first texture structure may include a non-pyramid structure, and the second texture structure may include a pyramid structure. Alternatively, both the first and second texture structures may include non-pyramid-shaped structures.

10. The solar cell according to claim 1, characterized in that, The density of the first texture structure ranges from 1E3 to 3E4 per mm. 2 ; and / or, the density of the second texture structure ranges from 5E2 to 2E4 particles / mm. 2 ; and / or, the difference between the density of the first texture structure and the density of the second texture structure is greater than or equal to 2E2 particles / mm. 2 .

11. A solar cell module, characterized in that, include: The solar cell according to any one of claims 1 to 10.

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