Solar cell and solar cell module

Abstract

The utility model is suitable for the technical field of solar cells, and provides a solar cell and a solar cell module, the solar cell comprises a silicon substrate, the silicon substrate comprises a substrate front side close to sunlight and a substrate back side away from sunlight; the back surface of the substrate comprises first doped regions, second doped regions and isolation regions, wherein the first doped regions and the second doped regions are alternately distributed at intervals; at least one of the silicon substrate in the first doped region and the silicon substrate in the second doped region comprises a first suede structure, the silicon substrate in the isolation region comprises a second suede structure, the tower footing size of the first suede structure and the tower footing size of the second suede structure are both larger than 1 micron, the included angle between the side face of the first suede structure and the tower footing is a first angle, and the included angle between the side face of the second suede structure and the tower footing is a second angle. The included angle between the side face of the second suede structure and the tower footing is a second angle, and the first angle is smaller than the second angle. According to the solar cell provided by the utility model, the double-sided rate of the solar cell, the power generation efficiency of the back surface of the substrate and the photoelectric conversion efficiency of the assembly can be improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of solar cells, and in particular relates to a solar cell and a solar cell assembly. Background Art

[0002] A back-contact cell refers to a solar cell in which the light-receiving side of the cell has no electrode, and both the positive electrode and the negative electrode are arranged on the backlight side of the cell. This can reduce the shading of the cell by the electrodes, increase the short-circuit current of the cell, and improve the energy conversion efficiency of the cell.

[0003] In existing back-contact cells, the light utilization rate on the backlight side is reduced, and the surface structure of the doped region is not conducive to improving the photoelectric conversion efficiency of the back-contact cell. Utility Model Content

[0004] The utility model provides a solar cell and a solar cell assembly, aiming to solve the problem that the surface structure of the doped region on the backlight side of the existing back contact cell is not conducive to improving the photoelectric conversion efficiency of the back contact cell.

[0005] The utility model provides a solar cell, comprising: a silicon substrate, wherein the silicon substrate comprises a substrate front surface close to sunlight and a substrate back surface away from the sunlight;

[0006] The back side of the substrate comprises a first doping region and a second doping region that are alternately distributed, and an isolation region between the first doping region and the second doping region;

[0007] Wherein, the first doping region and the second doping region have opposite conductivity types;

[0008] At least one of the silicon substrate in the first doping region and the silicon substrate in the second doping region includes a first velvet structure, and the silicon substrate in the isolation region includes a second velvet structure. The base size of the first velvet structure and the base size of the second velvet structure are both greater than 1 μm. The angle between the side surface of the first velvet structure and the base of the first velvet structure is a first angle, and the angle between the side surface of the second velvet structure and the base of the second velvet structure is a second angle. The first angle is smaller than the second angle.

[0009] In some embodiments, an absolute value of a difference between a tower base size of the first pile structure and a tower base size of the second pile structure is less than 0.2 μm.

[0010] In some embodiments, the first velvet structure is an inverted pyramid velvet structure.

[0011] In some embodiments, the first angle is 10° to 20°, and the second angle is 50° to 58°.

[0012] In some embodiments, a height of the first doping region relative to the isolation region is 4 μm to 6 μm.

[0013] In some embodiments, a height of the second doping region relative to the isolation region is 2 μm to 3 μm.

[0014] In some embodiments, a height of the first doping region relative to the isolation region is greater than a height of the second doping region relative to the isolation region.

[0015] In some embodiments, two opposite surfaces of the silicon substrate in the first doping region and the silicon substrate in the second doping region have a corrugated structure.

[0016] In some embodiments, the first doped region includes an amorphous silicon layer or a microcrystalline silicon layer; and the second doped region includes an amorphous silicon layer or a microcrystalline silicon layer.

[0017] The utility model also provides a solar cell assembly, comprising: the solar cell as described in any one of the above items.

[0018] The solar cell and solar cell module provided by the utility model set the silicon substrate in the first doping area and / or the silicon substrate in the second doping area with a first velvet structure, and set the silicon substrate in the isolation area with a second velvet structure, which can improve the bifaciality of the solar cell, the power generation efficiency of the back side of the substrate, and the photoelectric conversion efficiency of the module, and the first angle corresponding to the first velvet structure is smaller than the second angle of the second velvet structure, which can improve the passivation effect of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of a solar cell provided by an embodiment of the present utility model;

[0020] Figure 2 It is a structural schematic diagram of a solar cell assembly provided by an embodiment of the utility model. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] References to "embodiments" or "implementations" in this disclosure mean that a particular feature, component, or characteristic described in connection with an embodiment or implementation may be included in at least one embodiment of the disclosure. The appearance of such phrases in various places in the specification does not necessarily refer to the same embodiment, nor do they constitute independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0023] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0024] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, or mutual communication; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0025] In related technologies, solar cells are devices that convert sunlight into electrical energy. Specifically, solar cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using electrodes, thereby facilitating the efficient use of electrical energy. When both the positive and negative electrodes of a solar cell are located on the back side of the solar cell, the solar cell is considered a back-contact cell. Because back-contact cells have no metal electrodes blocking the front side, they have a higher short-circuit current and are currently one of the technological directions for achieving high-efficiency crystalline silicon cells.

[0026] The following combination Figures 1 to 2 , the solar cell and solar cell assembly provided by the embodiment of the utility model are described in detail through specific embodiments and their application scenarios.

[0027] Figure 1 It is a schematic structural diagram of a solar cell provided by an embodiment of the utility model.

[0028] like Figure 1 As shown, an embodiment of the present invention provides a solar cell, comprising:

[0029] A silicon substrate 10, comprising a front side of the substrate facing toward sunlight and a back side of the substrate facing away from sunlight;

[0030] The back side of the substrate includes first doping regions 11 and second doping regions 12 that are alternately distributed, and an isolation region 13 between the first doping regions 11 and the second doping regions 12;

[0031] The first doping region 11 and the second doping region 12 have opposite conductivity types;

[0032] At least one of the silicon substrate in the first doping region 11 and the silicon substrate in the second doping region 12 includes a first velvet structure, and the silicon substrate in the isolation region 13 includes a second velvet structure. The tower base size of the first velvet structure and the tower base size of the second velvet structure are both greater than 1 μm. The angle between the side surface of the first velvet structure and the tower base of the first velvet structure is a first angle, and the angle between the side surface of the second velvet structure and the tower base of the second velvet structure is a second angle. The first angle is smaller than the second angle.

[0033] It should be noted that the solar cell can be a back-contact cell, which includes at least a silicon substrate 10. Silicon substrate 10 can be an N-type substrate doped with phosphorus or a P-type substrate doped with boron, without specific limitation herein. Silicon substrate 10 includes a front side and a back side, where the back side is the backlight side and the front side is the light-receiving side.

[0034] Optionally, the front side of the substrate can be a velvet structure or a polished surface structure. Since the velvet structure has a light-trapping effect, when the front side of the substrate is a velvet structure, the reflectivity of the front side of the substrate can be reduced. The velvet structure allows more light to be refracted from the light-receiving surface into the silicon substrate 10 and absorbed and utilized by the silicon substrate 10, which is beneficial to improving the photoelectric conversion efficiency of the solar cell.

[0035] Optionally, the back side of the substrate may include first doping regions 11 and second doping regions 12 that are arranged in a staggered manner, and isolation regions 13 between adjacent first doping regions 11 and second doping regions 12 .

[0036] In actual implementation, the conductivity type of the first doping region 11 may be opposite to that of the silicon substrate 10 , or the conductivity type of the first doping region 11 may be the same as that of the silicon substrate 10 .

[0037] A first doped semiconductor layer is formed in the first doping region 11, and the first doped semiconductor layer is a crystalline semiconductor layer containing a first doping element. A second doped semiconductor layer is formed in the second doping region 12, and the second doped semiconductor layer is a crystalline semiconductor layer containing a second doping element. The doping element can be an N-type dopant such as a Group V element including phosphorus (P), arsenic (As), bismuth (Bi), antimony (Sb), or a P-type dopant including a Group III element including boron (B), aluminum (Al), gallium (Ga), indium (In). The first doping element and the second doping element have opposite conductivity types, and thus the first doped semiconductor layer and the second doped semiconductor layer have opposite conductivity types.

[0038] Therefore, no matter which of the above structures the specific structure of the solar cell is, the back side of the silicon substrate 10 has a first doping region 11 and a second doping region 12 with opposite conductivity types, and the two doping regions with opposite conductivity types are separated and alternately distributed using an isolation region 13, thereby avoiding short circuits between the positive and negative electrodes of the solar cell or battery leakage, and improving battery reliability.

[0039] As a possible method, in the actual manufacturing process of the above-mentioned solar cell, a doped semiconductor layer can be first formed on the back side of the silicon substrate 10, and then the doped semiconductor layer located in the backlight side area can be selectively removed to obtain the above-mentioned first doped semiconductor layer. Correspondingly, the above-mentioned method can also be used to form a second doped semiconductor layer on the local area of ​​the backlight side. Figure 1 As shown, in order to prevent the first doping region 11 and the second doping region 12 from being conductive and causing a short circuit, the existing manufacturing method forms an isolation region 13 with a certain width between the two by wet chemical etching or other methods.

[0040] Optionally, a pattern corresponding to the first doped region 11, the second doped region 12, and the isolation region 13 can be formed on the back side of the silicon substrate 10 using techniques such as photolithography or laser etching. After the mask layer is prepared, the first doping element and the second doping element are used to complete the doping of the corresponding regions. Due to the presence of the mask layer, only the areas not covered by the mask are doped to form the first doped semiconductor layer and the second doped semiconductor layer, thereby forming the first doped region 11 and the second doped region 12, which are alternately distributed, and the isolation region 13 located between the first doped region 11 and the second doped region 12 on the back side of the substrate.

[0041] The solar cell provided by the embodiment of the present invention sets at least two of the silicon substrate in the first doping region 11, the silicon substrate in the second doping region 12, and the silicon substrate in the isolation region 13 to a velvet structure. The velvet structure enables at least two of the above to have a higher specific surface area and light trapping effect.

[0042] Optionally, the silicon substrate 10 in at least one of the first doping region 11 and the second doping region 12 includes a first velvet structure, and the silicon substrate 10 in the isolation region 13 includes a second velvet structure. Both the first velvet structure and the second velvet structure are pyramid velvet structures, but their structural parameters are different.

[0043] In some embodiments, the first texture structure is an inverted pyramid texture structure.

[0044] In actual implementation, the first velvet structure can be an inverted pyramid velvet structure or a normal pyramid velvet structure. A number of concave structures can also be set on the surface of the inverted pyramid velvet structure or the normal pyramid velvet structure to increase the propagation path of light in the velvet structure, so that the light is not easily reflected directly, and the escaping light will be greatly reduced, thereby improving light absorption, reducing light reflectivity, and thereby improving the photoelectric conversion efficiency of solar cells.

[0045] It can be understood that the silicon substrate 10 in the first doping region 11 and / or the second doping region 12 , and the silicon substrate 10 in the isolation region 13 all include a plurality of pyramid velvet structures with different base sizes.

[0046] The tower base refers to the bottom surface of the pyramid velvet structure, and the tower base size refers to the maximum distance between two points on the bottom surface of the pyramid velvet structure. For example, if the tower base is a quadrilateral, the tower base size can be the distance between two diagonal points of the quadrilateral. For example, the tower base size can be 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, or any value between 0.5 μm and 3.5 μm.

[0047] The first velvet structure is a pyramid velvet structure with a tower base size greater than 1 μm, and the second velvet structure is a pyramid velvet structure with a tower base size greater than 1 μm. The first velvet structure is located in the first doping region 11 and / or the second doping region 12, and the second velvet structure is located in the isolation region 13.

[0048] The pyramid velvet structure has a bottom surface and a side surface. The angle between the side surface of the first velvet structure and the tower base is a first angle. The angle between the side surface of the second velvet structure and the tower base is a second angle. The first angle is smaller than the second angle.

[0049] It should be noted that the smaller the angle between the side of the pyramid velvet structure and the base, the larger the top angle of the pyramid velvet structure, the "flatter" the pyramid velvet structure, and the higher the light reflectivity; the larger the angle between the side of the pyramid velvet structure and the base, the smaller the top angle of the pyramid velvet structure, and the lower the light reflectivity.

[0050] In some embodiments, an absolute value of a difference between a tower base size of the first texture structure and a tower base size of the second texture structure is less than 0.2 μm.

[0051] It should be noted that the difference between the tower base size of the first velvet structure and the tower base size of the second velvet structure ranges from -0.2 μm to 0.2 μm. Therefore, in a velvet structure with a tower base size greater than 1 μm, the difference between the first and second velvet structures is small, which can improve the uniformity of the velvet structure, enhance the passivation effect, and thus reduce reflectivity.

[0052] like Figure 1 As shown, as a case, the first doped semiconductor layer and the second doped semiconductor layer are polysilicon layers 15, which are deposited on the surface of the silicon substrate 10, and a tunneling oxide layer 14 (SiO x ) to achieve passivation of the silicon surface and selective transport of charge carriers. This structure can effectively reduce recombination losses on the silicon surface and improve the efficiency of the solar cell. The isolation region 13 does not have a tunneling oxide layer 14 or a polysilicon layer 15 deposited therein.

[0053] In order to ensure better passivation effect of the first doping region 11 and the second doping region 12 , the first angle corresponding to the first texture structure may be smaller than the second angle corresponding to the second texture structure.

[0054] In some embodiments, the first angle is 10° to 20°, and the second angle is 50° to 58°.

[0055] In actual implementation, when the first angle is any angle between 10° and 20° and the second angle is any angle between 50° and 58°, the solar cell has excellent passivation effect and low reflectivity, ensuring high light utilization on the back side of the substrate.

[0056] The first angle may be, for example, 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, or 20°. The second angle may be, for example, 50°, 51°, 52°, 53°, 54°, 55°, 56°, 57°, or 58°. Preferably, the first angle is 15° and the second angle is 54°.

[0057] In some embodiments, a height of the first doping region 11 relative to the isolation region 13 is greater than a height of the second doping region 12 relative to the isolation region 13 .

[0058] In actual implementation, the isolation region 13 on the back side of the substrate can isolate the first doped region 11 from the second doped region 12, reducing the carrier recombination rate at the lateral boundary between the first doped region 11 and the second doped region 12, thereby improving the photoelectric conversion efficiency of the solar cell. Secondly, the height of the first doped region 11 relative to the isolation region 13 is greater than the height of the second doped region 12 relative to the isolation region 13. This helps to offset at least part of the first doped region 11 and the second doped region 12 along the thickness direction of the silicon substrate 10, further reducing the risk of leakage on the backlight side and improving the electrical reliability of the solar cell.

[0059] In the solar cell provided by the embodiment of the present invention, the first side surface of the isolation region 13 adjacent to the first doped region 11 and the second side surface of the isolation region 13 adjacent to the second doped region 12 include a corrugated structure. The first side surface and the second side surface are the two opposing surfaces between the first doped region 11 and the second doped region 12.

[0060] The solar cell provided by the embodiment of the present invention facilitates more light to be refracted from the first side surface corresponding to the first doped region 11 and the second side surface corresponding to the second doped region 12 into the silicon substrate 10 and utilized by the silicon substrate 10, thereby facilitating improvement of the photoelectric conversion efficiency of the solar cell.

[0061] Since the first side surface is located between the isolation region 13 and the first doping region 11, and the second side surface is located between the isolation region 13 and the second doping region 12, as the boundary area of ​​different structures, the corrugated structure formed on the entire first side surface and the second side surface can make the area where the first side surface and the second side surface are located darker, which is beneficial to improving the contrast of the captured image, thereby improving the yield of battery production.

[0062] In some embodiments, the distance between two opposite surfaces of the first doping region 11 and the second doping region 12 is 50 μm to 80 μm.

[0063] In practice, the isolation region 13 can isolate the first doped region 11 and the second doped region 12 of opposite conductivity types, thereby suppressing leakage. Therefore, the size of the isolation region 13 on the back side of the substrate can be determined based on the leakage prevention spacing requirements of the first doped region 11 and the second doped region 12 in actual application scenarios.

[0064] It is understood that the two opposing surfaces of the first doping region 11 and the second doping region 12 refer to the distance between the first side surface corresponding to the first doping region 11 and the second side surface corresponding to the second doping region 12. Setting this distance between 50 μm and 80 μm significantly reduces leakage. For example, it can be 50 μm, 60 μm, 70 μm, 80 μm, or any value between 50 μm and 80 μm, and is not specifically limited here.

[0065] In some embodiments, the height of the first doping region 11 relative to the isolation region 13 is 4 μm to 6 μm.

[0066] It can be understood that the height of the first doped region 11 relative to the isolation region 13 can be set according to actual needs. For example, the height of the first doped region 11 relative to the isolation region 13 can be greater than or equal to 4μm and less than or equal to 6μm, and can be 4μm, 5μm or 6μm, etc., which is not specifically limited here.

[0067] In some embodiments, the height of the second doping region 12 relative to the isolation region 13 is 2 μm to 3 μm.

[0068] It can be understood that the height of the second doping region 12 relative to the isolation region 13 can be set according to actual needs. For example, the height of the second doping region 12 relative to the isolation region 13 can be greater than or equal to 2μm and less than or equal to 3μm, and can be 2μm, 2.5μm or 3μm, etc., which is not specifically limited here.

[0069] Optionally, two opposite surfaces of the silicon substrate in the first doping region 11 and the silicon substrate in the second doping region 12 have a corrugated structure.

[0070] In some cases, the first and second opposing surfaces of the first and second doped regions 11, 12, i.e., the first and second opposing surfaces, have a corrugated structure. The corrugated structure includes a triangular prism-like structure, and the cross-section of the opposing surfaces of the first and second doped regions 11, 12 along the back surface of the substrate may be sawtooth-shaped. The corrugated structure is a polyhedral structure that helps increase the specific surface area of ​​the first and second opposing surfaces, further reducing the light reflectivity of the opposing surfaces of the first and second doped regions 11, 12.

[0071] In some embodiments, when at least two of the silicon substrate in the first doping region 11, the silicon substrate in the second doping region 12, and the silicon substrate in the isolation region 13 are set to a velvet structure and the velvet structure is a pyramid-shaped structure, it is beneficial to increase the specific surface area of ​​the above at least two, and can further increase the roughness of the above at least two, thereby helping to reduce the light reflectivity of the above at least two.

[0072] In some embodiments, as Figure 1 As shown, the solar cell further includes a passivation layer 16, which is stacked on the polysilicon layer 15, on the silicon substrate 10 in the isolation region 13, and on the first side surface between the first doped region 11 and the isolation region 13 and on the second side surface between the second doped region 12 and the isolation region 13.

[0073] Specifically, the passivation layer 16 may be made of one or more of silicon oxide, aluminum oxide, hafnium oxide, silicon nitride or silicon oxynitride, which is not specifically limited here.

[0074] In some embodiments, the first doping region 11 includes an amorphous silicon layer or a microcrystalline silicon layer; and the second doping region 12 includes an amorphous silicon layer or a microcrystalline silicon layer.

[0075] In actual implementation, the polysilicon layer 15 in the above embodiment can be replaced by an amorphous silicon layer or a microcrystalline silicon layer. Using a microcrystalline silicon layer or an amorphous silicon layer to implement contact passivation has better hydrogen passivation effect, which can improve the photoelectric conversion efficiency of the solar cell and reduce the cost of electricity.

[0076] like Figure 2 As shown, the present invention further provides a solar cell assembly 100, comprising: a solar cell 101 as described in any of the above embodiments.

[0077] The solar cell 101 has been described in detail in the above embodiment and will not be described again here.

[0078] The solar cell assembly provided by the embodiment of the present invention sets a first velvet structure on the silicon substrate in the first doping region and / or the silicon substrate in the second doping region, and sets a second velvet structure on the silicon substrate in the isolation region, which can improve the bifaciality of the solar cell, the power generation efficiency of the back side of the substrate, and the photoelectric conversion efficiency of the assembly, and the first angle corresponding to the first velvet structure is smaller than the second angle of the second velvet structure, which can improve the passivation effect of the solar cell.

[0079] It is understandable that those skilled in the art can, under the guidance of the above embodiments, combine various implementation methods in the above embodiments to obtain technical solutions of multiple implementation methods.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A solar cell, characterized in that: include: A silicon substrate, the silicon substrate comprising a substrate front surface close to sunlight and a substrate back surface facing away from the sunlight; The back side of the substrate comprises a first doping region and a second doping region that are alternately distributed, and an isolation region between the first doping region and the second doping region; Wherein, the first doping region and the second doping region have opposite conductivity types; At least one of the silicon substrate in the first doping region and the silicon substrate in the second doping region includes a first velvet structure, and the silicon substrate in the isolation region includes a second velvet structure. The base size of the first velvet structure and the base size of the second velvet structure are both greater than 1 μm. The angle between the side surface of the first velvet structure and the base of the first velvet structure is a first angle, and the angle between the side surface of the second velvet structure and the base of the second velvet structure is a second angle. The first angle is smaller than the second angle.

2. The solar cell according to claim 1, wherein An absolute value of a difference between a tower base size of the first texture structure and a tower base size of the second texture structure is less than 0.2 μm.

3. The solar cell according to claim 1, wherein The first velvet structure is an inverted pyramid velvet structure.

4. The solar cell according to claim 1, wherein The first angle is 10° to 20°, and the second angle is 50° to 58°.

5. The solar cell according to any one of claims 1 to 4, characterized in that: The height of the first doping region relative to the isolation region is 4 μm to 6 μm.

6. The solar cell according to any one of claims 1 to 4, characterized in that: The height of the second doping region relative to the isolation region is 2 μm to 3 μm.

7. The solar cell according to any one of claims 1 to 4, characterized in that: A height of the first doping region relative to the isolation region is greater than a height of the second doping region relative to the isolation region.

8. The solar cell according to any one of claims 1 to 4, characterized in that: Two opposite surfaces of the silicon substrate in the first doping region and the silicon substrate in the second doping region have a corrugated structure.

9. The solar cell according to any one of claims 1 to 4, characterized in that: The first doping region includes an amorphous silicon layer or a microcrystalline silicon layer; the second doping region includes an amorphous silicon layer or a microcrystalline silicon layer.

10. A solar cell module, characterized in that: include: The solar cell according to any one of claims 1 to 9.

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