A solar cell, a stacked cell, and a photovoltaic module

Abstract

This application discloses a solar cell, a tandem solar cell, and a photovoltaic module. The solar cell includes a silicon substrate. The silicon substrate includes a first surface and a second surface disposed opposite to each other. The first surface includes a first region and a second region spaced apart. The surface height of the silicon substrate at the first region is lower than the surface height of the silicon substrate at the second region, so that a step is formed at the boundary between the first region and the second region. An electrode structure is also provided on the first surface, corresponding to the first region and extending to the step. Blind slot structures are distributed on the step, extending in a direction parallel to the thickness direction of the silicon substrate. The method for fabricating the solar cell of the present invention optimizes the interface of the step region, reduces optical loss at the edge of the cell, improves light absorption efficiency, and improves the conversion efficiency of the solar cell.

Description

Technical Field

[0001] This application relates to the field of photovoltaic cell technology, and in particular to a solar cell, a tandem cell, and a photovoltaic module. Background Technology

[0002] Top-conducting oxide (TOPCon) technology is one of the mainstream high-efficiency technologies in the current photovoltaic (PV) cell field. Its core principle is to deposit an ultrathin oxide layer (SiOx) and a doped polycrystalline silicon layer (Poly-Si) on the back of the silicon wafer, effectively reducing the carrier recombination rate on the silicon surface and significantly improving the open-circuit voltage (Voc) and fill factor (FF) of the cell, thereby increasing the cell's conversion efficiency. In existing technologies, PolyFinger structures are typically fabricated using laser processing, and the mass production conversion efficiency of TOPCon cells has reached approximately 25.8%. However, in existing solar cell structures, the surface at the interface between the laser-processed and non-laser-processed areas reflects light significantly, affecting light absorption and causing substantial optical losses on the cell surface. This also greatly diminishes the optimization effect of the PolyFinger structure.

[0003] Therefore, how to provide a solar cell that can reduce optical loss, improve light absorption and increase conversion efficiency, as well as a tandem cell and photovoltaic module incorporating such a solar cell, are urgent problems to be solved. Summary of the Invention

[0004] The purpose of this application is to solve the above-mentioned problems and provide a solar cell, a tandem cell, and a photovoltaic module; the method for preparing the solar cell optimizes the Poly Finger structure, optimizes the interface of the stepped region, reduces optical loss at the edge of the cell, improves the light absorption efficiency, and improves the conversion efficiency of the solar cell.

[0005] To solve the above-mentioned technical problems, the technical solution adopted in this application is as follows: In a first aspect, this application provides a solar cell comprising a silicon substrate; the silicon substrate includes a first surface and a second surface disposed opposite to each other, the first surface including a first region and a second region spaced apart; the surface height of the silicon substrate at the first region is lower than the surface height of the silicon substrate at the second region, such that the boundary region between the first region and the second region forms a stepped portion; an electrode structure is further provided on the first surface, the electrode structure corresponding to the first region and extending to the stepped portion; a blind slot structure is distributed on the stepped portion, the blind slot structure extending along a direction parallel to the thickness direction of the silicon substrate.

[0006] Optionally, the blind groove structure includes a side notch blind groove structure at least located on the side of the stepped portion near the first region, and a fully blind groove structure at least located on the side of the stepped portion near the second region.

[0007] Optionally, the blind groove structure includes a closed end disposed near the surface of the first region and an open end disposed near the surface of the second region, wherein the cross-sectional area of ​​the open end is larger than the cross-sectional area of ​​the closed end, and the open end is in the shape of an inverted pyramid or a near-inverted pyramid.

[0008] Optionally, the side notch blind groove includes a separately provided independent side notch blind groove and / or a side notch blind groove group formed by at least two of the side notch blind grooves communicating with each other; the notch of the independent side notch blind groove faces the first region, and the notch of at least one of the side notch blind grooves in the side notch blind groove group faces the first region.

[0009] Optionally, a edging structure is provided between the stepped portion and the second region. The edging structure is at least located on the side of the blind cell structure near the second region. The solar cell further includes a tunneling layer and a polycrystalline silicon layer stacked sequentially on the surface of the second region. The sides of the tunneling layer and the polycrystalline silicon layer near the first region extend to the side of the edging structure near the second region.

[0010] Optionally, the width of the edging structure is 0.5-2μm.

[0011] Optionally, the height difference between the surface of the first region and the surface of the second region is 0.1-3 μm.

[0012] Optionally, the stepped portion includes a sidewall connecting the surface of the first region and the surface of the second region, and the blind groove structure is disposed on the sidewall; the angle between the sidewall and the surface of the first region is an obtuse angle.

[0013] Secondly, this application provides a stacked battery, comprising: Top cell, which can be a perovskite cell, cadmium telluride solar cell, copper indium gallium selenide solar cell, or gallium arsenide solar cell; Intermediate connecting layer; and, The bottom battery is a solar cell as described above; The top battery, the intermediate connecting layer, and the bottom battery are stacked and connected.

[0014] Thirdly, this application provides a photovoltaic module, which includes the solar cell described above, or the tandem cell described above.

[0015] The beneficial effects of this application include at least the following: The solar cell of the present invention includes a first region and a second region having the stepped portion formed thereon. The stepped portion is located at the boundary between the first region and the second region. The blind slot structure is distributed on the stepped portion. The blind slot structure forms a non-planar structure on the stepped region. By optimizing the structure at the boundary between the first region and the second region, the surface reflection effect of the boundary between the first region and the second region on light is avoided, the light absorption rate is improved, the optical loss of the solar cell is reduced, and the conversion efficiency of the solar cell is improved. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the solar cell of the present invention.

[0017] Figure 2 This is a first scanning electron microscope (SEM) image of the first surface of the silicon substrate of the present invention.

[0018] Figure 3 This is a schematic diagram of the first structure of the first surface of the silicon substrate of the present invention.

[0019] Figure 4 This is a second scanning electron microscope (SEM) image of the first surface of the silicon substrate of the present invention.

[0020] Figure 5 This is a schematic diagram of a second structure of the first surface of the silicon substrate of the present invention.

[0021] Figure 6 This is a schematic diagram of a first partial structure of the silicon substrate of the present invention.

[0022] Figure 7 This is a schematic diagram of a second partial structure of the silicon substrate of the present invention.

[0023] Figure 8 This is another structural schematic diagram of the solar cell of the present invention.

[0024] Figure 9 This is a schematic diagram of the structure of the battery string in the photovoltaic module of the present invention.

[0025] Figure 10 This is a schematic diagram of the structure of the photovoltaic module of the present invention. Detailed Implementation

[0026] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0027] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0028] In this application, the use of terms such as "first" and "second" is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0029] In a first aspect, the present invention provides a solar cell 110, see [link to previous document]. Figures 1 to 5 As shown, the solar cell includes a silicon substrate 1; the silicon substrate 1 includes a first surface a and a second surface b disposed opposite to each other, the first surface a includes a first region 11 and a second region 12 distributed at intervals; the surface height of the silicon substrate 1 at the first region 11 is lower than the surface height of the silicon substrate 1 at the second region 12, so that the boundary region 13 between the first region 11 and the second region 12 forms a step portion 14; an electrode structure is also provided on the first surface, the electrode structure corresponds to the first region and extends to the step portion, and a blind groove structure 141 is distributed on the step portion 14, the blind groove structure 141 extending in a direction parallel to the thickness direction of the silicon substrate 1. It should be noted that, in this invention, the first surface a and the second surface b refer to two planes disposed opposite to each other on both sides of the silicon substrate 1 along the thickness direction of the silicon substrate. The first surface a or the second surface b described below are for ease of description only and should not be construed as the sole limitation on the location of the step portion 14 and the blind groove structure 141. If the structural arrangement on the second surface b side needs to solve the same technical problem as that to be solved by the present invention, the structural improvement scheme of the first region 11 and the second region 12 is also applicable to the second surface b.

[0030] The solar cell 110 provided by the present invention includes a first region 11 and a second region 12 formed on the stepped portion 14. The stepped portion 14 is disposed at the junction region 13 of the first region 11 and the second region 12. The blind slot structure 141 is distributed on the stepped portion 14. The blind slot structure 141 forms a non-planar structure on the stepped portion 14. By optimizing the structure at the junction of the first region 11 and the second region 12, the reflection effect of the surface of the junction region 13 of the first region 11 and the second region 12 on light is avoided, the light absorption rate is improved, the optical loss of the solar cell 110 is reduced, and the conversion efficiency of the solar cell 110 is improved.

[0031] The depth of the blind trench structure 141 extending along the thickness direction of the silicon substrate 1 is less than or equal to the height difference between the surface of the silicon substrate 1 in the first region 11 and the surface of the silicon substrate 1 in the second region 12.

[0032] Optional, see Figures 2 to 5 As shown, the blind groove structure 141 includes a side-notch blind groove structure 1411 at least located on the side of the stepped portion 14 near the first region 11, and a complete blind groove structure 1412 at least located on the side of the stepped portion 14 near the second region 12. It can be understood that the side-notch blind groove structure 1411 is formed because, when the blind groove structure 141 is close to the first region 11, the connection area between the side of the blind groove structure 141 near the first region 11 and the stepped portion 14 is lower than the side of the blind groove structure 141 near the second region 12. The blind groove structure 141 is located approximately close to the first region 11; the larger the boundary area between the blind groove structure 141 and the side of the stepped portion 14 near the first region 11, the larger the notch area of ​​the side-notch blind groove structure 1411.

[0033] Optionally, the volumes of the various side-notch blind groove structures 1411 are not entirely the same, and the volumes of the various complete blind groove structures 1412 are also not entirely the same. The number of side-notch blind groove structures 1411 and the number of complete blind groove structures 1412 can be specifically set according to actual needs.

[0034] Optionally, the blind groove structure 141 includes a closed end 1413 disposed near the surface of the first region 11 and an open end 1414 disposed near the surface of the second region 12, wherein the cross-sectional area of ​​the open end 1414 is larger than the cross-sectional area of ​​the closed end 1413; in some embodiments, the overall shape of the blind groove structure 141 is an inverted pyramid or a near-inverted pyramid.

[0035] Optionally, the side notch blind groove structure 1411 includes a separately provided independent side notch blind groove, and / or a side notch blind groove group formed by at least two side notch blind groove structures 1411 interconnected; the notch of the independent side notch blind groove faces the first region 11, and the notch of at least one side notch blind groove in the side notch blind groove group faces the first region 11.

[0036] Optional, see Figures 2 to 4 as well as Figure 7As shown, a edging structure 142 is provided between the stepped portion 14 and the second region 12. The edging structure 142 is at least located on the side of the blind trench structure 141 near the second region 12. The solar cell 110 also includes a tunneling oxide layer 101 and a doped polycrystalline silicon layer 102 sequentially stacked on the surface of the second region 12. The sides of the tunneling oxide layer 101 and the doped polycrystalline silicon layer 102 near the first region 11 both extend to the side of the edging structure 142 near the second region 12. The edging structure 142 further avoids light reflection, improves light utilization, and increases the conversion efficiency of the solar cell 110. At the same time, it increases the contact area between the first region 11 and the subsequently deposited layer structure, thereby improving the structural stability of the solar cell 110. Optionally, the height difference between the edging structure 142 and the surface of the second region 12 is 5-1000nm; for example, it can be 50nm, 100nm, 140nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, or 1000nm.

[0037] Optionally, the height difference between the surface of the first region 11 and the surface of the second region 12 is 0.1-3 μm; for example, it can be 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm.

[0038] Optional, see Figures 2 to 6 As shown, the stepped portion 14 further includes a sidewall 143 connecting the surface of the first region 11 and the surface of the second region 12, and the blind trench structure 141 is disposed on the sidewall 143; the angle between the sidewall 143 and the surface of the first region 11 is an obtuse angle. In some embodiments, the angle between the sidewall 143 and the surface of the first region 11 is greater than 90° and less than 175°. The sidewall 143 is inclined relative to the surface of the first region 11, which increases the contact area between the passivation layer disposed in the first region 11 and the silicon substrate 1, increases the connection strength between the passivation layer and the first region 11 and the stepped portion 14, increases the stability of the passivation layer and the subsequently fabricated electrode structure, and thus improves the structural stability and durability of the solar cell 110.

[0039] In some optional embodiments, the side-notch blind groove structure 1411 is at least provided on the sidewall 143, and the complete blind groove structure 1412 is at least provided on the area of ​​the step portion 14 near the second region 12. When the blind groove structure 141 is the side-notch blind groove structure 1411, the edging structure 142 is provided along the side of the side-notch blind groove structure 1411 near the second region 12; when the blind groove structure 141 is the complete blind groove structure 1412, the edging structure 142 is wrapped around the outer periphery of the complete blind groove.

[0040] For example, taking a TOPCon cell as an example, the structure of the solar cell 110 will be described in detail. See [link to documentation]. Figure 1 and Figure 8 As shown, the solar cell 110 includes the silicon substrate 1, a tunneling oxide layer 101, a doped polycrystalline silicon layer 102, a first passivation layer 103, a first antireflection layer 104, and a first electrode 105 sequentially stacked on a first surface a. The first electrode 105 is disposed in the second region 12 in the thickness direction of the silicon substrate 1. The solar cell 110 also includes a second passivation layer 106, a second antireflection layer 107, and a second electrode 108 sequentially stacked on the second surface b. The second electrode 108 is disposed in the second region 12.

[0041] In this design, the first surface a of the silicon substrate 1 is a back surface. The silicon substrate 1 includes a first region 11 and a second region 12 spaced apart. Along the direction from the second surface b to the first surface a, a tunneling oxide layer 101, a doped polysilicon layer 102, a first passivation layer 103, and a first antireflection layer 104 are sequentially deposited on the first surface a. A first electrode 105 is disposed in the region corresponding to the second region 12. In the thickness direction of the silicon substrate 1, the first electrode 105 extends sequentially through the first antireflection layer 104 and the first passivation layer 103 to the doped polysilicon layer 102 along the direction from the first surface a to the second surface b. The first electrode 105 is connected to the doped polysilicon layer 102. A step portion 14 is provided at the boundary region 13 between the first region 11 and the second region 12. The first passivation layer 103 covers the first region 11, the second region 12, and the step portion 14. The first passivation layer 103 also covers the blind trench structure 141 and the edge-sealing structure 142. The stepped portion 14 and the blind trench structure 141 enhance the bonding strength between the first passivation layer and the silicon substrate 1.

[0042] Wherein, the second surface b of the silicon substrate 1 is the positive surface, the emitter 109 is below the second region 12, the emitter may not be below the first region 11, the second antireflection layer 107 covers the second passivation layer 106, the second electrode 108 is disposed in the region where the second region 12 is located, the second electrode 108 extends through the second antireflection layer 107 and the second passivation layer 106 in the thickness direction of the silicon substrate 1 to the emitter 109 below the second region 12, and the second electrode 108 is connected to the emitter 109.

[0043] In some embodiments, the silicon substrate 1 can be an N-type semiconductor silicon substrate or a P-type semiconductor silicon substrate. The N-type semiconductor silicon substrate is doped with an N-type dopant element, which can be any one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor silicon substrate is doped with a P-type dopant element, which can be any one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0044] In some embodiments, the solar cell 110 can be a single-sided cell, with the front surface (second surface b) serving as the light-receiving surface for receiving incident light, and the back surface (first surface a) serving as the backlight surface.

[0045] In some embodiments, the solar cell 110 can be a bifacial cell, meaning that both the second surface b and the first surface a of the silicon substrate 1 can serve as light-receiving surfaces and can be used to receive incident light. The back surface (first surface a) can also receive incident light, but its efficiency in receiving incident light is somewhat lower than that of the light-receiving surface (second surface b).

[0046] In some embodiments, the emitter 109 may be formed by doping the original silicon substrate 1. The emitter 109 and the silicon substrate 1 are made of the same base material. Specifically, a portion of the thickness of the original silicon substrate 1 corresponding to the second region 12 may be doped. The doped original silicon substrate 1 serves as the emitter 109, and the undoped original silicon substrate 1 serves as the silicon substrate 1. Furthermore, the doping element type in the emitter 109 is different from the doping element type in the silicon substrate 1. For example, if the silicon substrate 1 is an N-type silicon substrate, the emitter 109 is formed by P-type doping of a portion of the thickness of the N-type silicon substrate.

[0047] In some embodiments, the second passivation layer 106 can be a single-layer structure or a stacked structure, and the material used to prepare the second passivation layer 106 can be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0048] In some embodiments, the material used to prepare the second antireflection layer 107 can be one or more of silicon nitride or silicon oxynitride.

[0049] In some embodiments, the tunneling oxide layer 101 may be a silicon dioxide layer.

[0050] In some embodiments, the doping type of the doped polysilicon layer 102 is the same as the doping type of the silicon substrate 1. For example, if the silicon substrate 1 is doped with an N-type dopant, then the doped polysilicon layer 102 is doped with an N-type dopant. The tunneling oxide layer 101 and the doped polysilicon layer 102 together form a passivation contact structure.

[0051] In some embodiments, the first passivation layer 103 can be a single-layer structure or a stacked structure, and the material used to prepare the first passivation layer 103 can be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0052] In some embodiments, the material used to prepare the first antireflection layer 104 may be one or more of silicon nitride or silicon oxynitride.

[0053] In some embodiments, the second electrode 108 has the opposite polarity to the first electrode 105.

[0054] In some optional embodiments, the method for fabricating the solar cell 110 includes the following steps: S1, a silicon substrate 1 is provided; wherein the silicon substrate 1 includes a first surface a and a second surface b disposed opposite to each other along its thickness direction.

[0055] S2, laser etching is performed on the first surface a of the silicon substrate 1 provided in step S1 to form a laser-processed area on the first surface a; the area not laser-etched is the non-laser-processed area; the surface height of the laser-processed area is lower than the surface height of the non-laser-processed area, so that a height difference is formed between the surfaces of the silicon substrate 1 of the laser-processed area and the non-laser-processed area.

[0056] S3, an alkaline etching solution is used to perform alkaline etching treatment on the laser processing area to remove the residual oxide layer and polysilicon in the obtained laser area. At the same time, the boundary area 13 between the obtained laser area and the non-laser area is etched to form a step portion 14 and an edge structure 142, and a blind groove structure 141 is formed in the step portion 14 area.

[0057] S4. After the alkaline etching treatment in step S3, the silicon substrate is passivated to form a passivation layer on the surface of the silicon substrate 1.

[0058] S5. The passivated cells in step S4 are subjected to electrode printing and sintering to obtain 110 solar cells.

[0059] In some optional embodiments, during step S2, the laser edge region uses less energy than the central region during laser etching, causing the connecting wall between the laser-processed area and the non-laser-processed area to be inclined; the angle between the connecting wall and the bottom surface of the laser-processed area is obtuse. In the subsequent alkaline etching process, the alkaline etching solution etches the laser-processed area, forming the first region 11 and the step portion 14. The region etched using a higher-energy laser in the laser-processed area corresponds to the first region 11, and the region etched using a lower-energy laser corresponds to the step portion 14. During the etching process, the alkaline etching solution etches the laser-processed area, causing the region formed by the lower-energy laser to be etched, ultimately forming the step portion 14 and the edge-binding structure 142. The formation of the fully grooved structure may be due to the following: during the alkaline corrosion process, as the corrosion proceeds, the alkaline corrosion solution gradually becomes ineffective, and the corrosion area on the silicon substrate 1 gradually decreases, thereby forming the fully grooved structure in the shape of an inverted pyramid on the silicon substrate 1.

[0060] Optionally, during the laser etching process, the energy density in the central region of the laser beam is 300-600 mJ / cm². 2 The energy density in the edge region of the laser beam is 50-400 mJ / cm². 2 .

[0061] Optionally, in some embodiments, the laser mold-making process uses a green picosecond laser with a power of 5-500W, a frequency of 200-5000k, a speed of 30-100m / s, and a wavelength of 532nm.

[0062] After the alkaline etching treatment in step S3, the etching depth of the laser area relative to the plane of the silicon substrate 1 is 0.1-3 μm.

[0063] The alkaline corrosive solution includes alkaline components and additives, wherein the alkaline components include one or both of sodium hydroxide and potassium hydroxide.

[0064] Secondly, embodiments of the present invention provide a stacked battery, which includes a top battery, an intermediate connecting layer and a bottom battery, wherein the top battery, the intermediate connecting layer and the bottom battery are stacked and connected in sequence.

[0065] The top cell is one of a perovskite cell, a cadmium telluride solar cell, a copper indium gallium selenide solar cell, or a gallium arsenide solar cell; the bottom cell is the solar cell 110 as described above.

[0066] In some implementations, the interlayer can be a transparent material with a high refractive index. To reduce light reflection and absorption at the interlayer interface and achieve good conductivity to minimize the impact of series resistance on device performance, the interlayer generally needs to have high light transmittance. For example, the interlayer can be a transparent conductive metal oxide thin film (ITO).

[0067] Thirdly, embodiments of the present invention provide a photovoltaic module, which includes the solar cell 110 as described above, or a tandem cell.

[0068] See Figure 9 and Figure 10 As shown, in some embodiments, the photovoltaic module includes a cell string 100, an encapsulating film 200, and a cover plate 300. Please refer to [link to relevant documentation]. Figure 10 As shown, the battery string 100 is formed by connecting multiple solar cells 110; the encapsulating film 200 is used to cover the surface of the battery string 100; the cover plate 300 is used to cover the surface of the encapsulating film 200 facing away from the battery string 100.

[0069] In some embodiments, the battery string 100 may also be formed by connecting multiple stacked batteries as described above.

[0070] In some embodiments, multiple solar cells 110 can be electrically connected by solder ribbons 120. The solder ribbons 120 connect adjacent solar cells 110, and are respectively connected to a first surface of the first solar cell 110 and a second surface of the second solar cell 110. The first surface is disposed on the same side as the first surface a of the silicon substrate, and the second surface is disposed on the same side as the second surface b of the silicon substrate.

[0071] In some embodiments, the solar cells 110 may be spaced apart, and during string bonding, the solder ribbon 120 extends from the first surface of the first solar cell 110 to the gap, passes through the gap, and extends to the second surface of the second solar cell 110.

[0072] In some embodiments, the encapsulating film 200 includes a first encapsulating film and a second encapsulating film. The first encapsulating film covers one of the first surface a or the second surface b of the solar cell 110, and the second encapsulating film covers the other of the first surface a or the second surface b of the solar cell 110. Specifically, at least one of the first encapsulating film or the second encapsulating film can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyethylene terephthalate (PET) film.

[0073] Example 1: Example 1 provides a solar cell 110 as described above. The solar cell 110 includes a silicon substrate 1, a tunneling oxide layer 101, a doped polycrystalline silicon layer 102, a first passivation layer 103, a first antireflection layer 104, and a first electrode 105 sequentially stacked on a first surface a. The first electrode 105 is disposed in the second region 12 corresponding to the thickness direction of the silicon substrate 1. The solar cell 110 also includes a second passivation layer 106, a second antireflection layer 107, and a second electrode 108 sequentially stacked on the second surface b. The second electrode 108 is disposed in the second region 12.

[0074] In this design, the first surface a of the silicon substrate 1 is a back surface. The silicon substrate 1 includes a first region 11 and a second region 12 spaced apart. Along the direction from the second surface b to the first surface a, a tunneling oxide layer 101, a doped polysilicon layer 102, a first passivation layer 103, and a first antireflection layer 104 are sequentially deposited on the first surface a. A first electrode 105 is disposed in the region corresponding to the second region 12. In the thickness direction of the silicon substrate 1, the first electrode 105 extends sequentially through the first antireflection layer 104 and the first passivation layer 103 to the doped polysilicon layer 102 along the direction from the first surface a to the second surface b. The first electrode 105 is connected to the doped polysilicon layer 102. A step portion 14 is provided at the boundary region 13 between the first region 11 and the second region 12. The first passivation layer 103 covers the first region 11, the second region 12, and the step portion 14. The first passivation layer 103 also covers the blind trench structure 141 and the edge-sealing structure 142.

[0075] Wherein, the second surface b of the silicon substrate 1 is the positive surface, the emitter 109 is below the second region 12, the emitter may not be below the first region 11, the second antireflection layer 107 covers the second passivation layer 106, the second electrode 108 is disposed in the region where the second region 12 is located, the second electrode 108 extends through the second antireflection layer 107 and the second passivation layer 106 in the thickness direction of the silicon substrate 1 to the emitter 109 below the second region 12, and the second electrode 108 is connected to the emitter 109.

[0076] Comparative Example 1: Comparative Example 1 provides a prior art solar cell 110. The only difference between Comparative Example 1 and Example 1 is that the solar cell 110 of Comparative Example 1 does not have a step portion 14 between the first region 11 and the second region 12.

[0077] The performance of the solar cells in Example 1 and Comparative Example 1 was compared and tested. The test conditions were as follows: using a pulsed solar simulator, at an ambient temperature of 25°C, AM1.5 atmospheric mass, and a solar irradiance of 1000 W / m², the electrical performance parameters of the cells, including photoelectric conversion efficiency (Eta), fill factor (FF), open-circuit voltage (Voc), and short-circuit current (Isc), were measured. The results are shown in Table 1. Table 1. Performance test comparison table of the embodiments and comparative examples.

[0078] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The above embodiments merely illustrate preferred implementations of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A solar cell, characterized in that, The device includes a silicon substrate; the silicon substrate includes a first surface and a second surface disposed opposite to each other, the first surface including a first region and a second region distributed at intervals; the surface height of the silicon substrate at the first region is lower than the surface height of the silicon substrate at the second region, so that the boundary region between the first region and the second region forms a step portion; an electrode structure is also provided on the first surface, the electrode structure corresponding to the first region and extending to the step portion; a blind groove structure is distributed on the step portion, the blind groove structure extending along a direction parallel to the thickness direction of the silicon substrate.

2. The solar cell according to claim 1, characterized in that, The blind groove structure includes a side notch blind groove structure at least located on the side of the stepped portion near the first region, and a complete blind groove structure at least located on the side of the stepped portion near the second region.

3. The solar cell according to claim 1, characterized in that: The blind groove structure includes a closed end disposed near the surface of the first region and an open end disposed near the surface of the second region. The cross-sectional area of ​​the open end is larger than the cross-sectional area of ​​the closed end, and the structure is inverted pyramid or similar to an inverted pyramid.

4. The solar cell according to claim 2, characterized in that: The side notch blind groove includes a separately provided independent side notch blind groove and / or a side notch blind groove group formed by at least two of the side notch blind grooves communicating with each other; the notch of the independent side notch blind groove faces the first region, and the notch of at least one of the side notch blind grooves in the side notch blind groove group faces the first region.

5. The solar cell according to claim 1, characterized in that: An edging structure is provided between the stepped portion and the second region. The edging structure is provided at least on the side of the blind cell structure near the second region. The solar cell also includes a tunneling layer and a polycrystalline silicon layer stacked sequentially on the surface of the second region. The sides of the tunneling layer and the polycrystalline silicon layer near the first region extend to the side of the edging structure near the second region.

6. The solar cell according to claim 5, characterized in that: The width of the edging structure is 0.5-2μm.

7. The solar cell according to claim 1, characterized in that: The height difference between the surface of the first region and the surface of the second region is 0.1-3 μm.

8. The solar cell according to claim 1, characterized in that: The stepped portion includes a sidewall connecting the surface of the first region and the surface of the second region, and the blind groove structure is disposed on the sidewall; the angle between the sidewall and the surface of the first region is an obtuse angle.

9. A stacked battery, characterized in that, include: Top cell, which can be a perovskite cell, cadmium telluride solar cell, copper indium gallium selenide solar cell, or gallium arsenide solar cell; Intermediate connection layer; and, The base cell is the solar cell according to any one of claims 1-8; The top battery, the intermediate connecting layer, and the bottom battery are stacked and connected.

10. A photovoltaic module, characterized in that, This includes the solar cell according to any one of claims 1-8, or the tandem cell according to claim 9.

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