Back-contact solar cell, photovoltaic module and photovoltaic system

Abstract

The present disclosure provides a back-contact solar cell, comprising P-type doped regions and N-type doped regions which are interdigitately arranged on the back surface of an N-type silicon substrate, and isolation regions located between the P-type doped regions and the N-type doped regions. The side of each P-type doped region close to the corresponding isolation region is provided with n1 recessed structures, and the side of each N-type doped region close to the corresponding isolation region is provided with n2 recessed structures, wherein n1>n2.

Description

Back contact solar cells, photovoltaic modules and photovoltaic systems

[0001] Cross-reference to related applications

[0002] This disclosure claims priority to Chinese patent application No. 202411017194.6, filed on July 26, 2024, with the China National Intellectual Property Administration (CNIPA) and entitled "Back Contact Solar Cell, Photovoltaic Module and Photovoltaic System"; claims priority to Chinese patent application No. 202411151681.1, filed on August 20, 2024, with the China National Intellectual Property Administration (CNIPA) and entitled "Back Contact Battery, Photovoltaic Module and Photovoltaic System"; and claims priority to Chinese patent application No. 202411231591.3, filed on September 3, 2024, with the China National Intellectual Property Administration (CNIPA) and entitled "Back Contact Battery, Photovoltaic Module and Photovoltaic System", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of solar cell technology, and more specifically, to a back-contact solar cell, a photovoltaic module, and a photovoltaic system. Background Technology

[0004] Interdigitated back contact (IBC) is a high-efficiency solar cell technology. In an IBC, the positive and negative metal electrodes are arranged in an interdigitated pattern on the back surface of the cell. This design eliminates any metal grid lines obstructing the front surface, maximizing the illuminated area, reducing optical losses, and improving short-circuit current and overall photoelectric conversion efficiency. To prevent direct contact between N-type and P-type doped regions, which would hinder effective carrier collection, an isolation region is placed at the boundary between them. As cell size decreases, the N-type and P-type doped regions are placed more closely, correspondingly reducing the size of the isolation region. However, an excessively narrow isolation region may not provide sufficient insulation protection, increasing the likelihood of short circuits and thus reducing the photoelectric conversion efficiency of the back contact cell. Furthermore, in traditional cross-back contact batteries, a surface passivation layer is usually formed on the back side of the battery to reduce the carrier recombination rate on the back side and improve the photoelectric conversion efficiency. However, the passivation effect of the surface passivation layer on the back side of the existing cross-back contact battery is not good, which is not conducive to improving the photoelectric conversion efficiency of the battery. Summary of the Invention

[0005] The main objective of this disclosure is to provide a back-contact solar cell, photovoltaic module, and photovoltaic system. These improvements enhance the isolation performance of different doped regions on the back surface of the back-contact cell, improve passivation, and increase the photoelectric conversion efficiency of the solar cell.

[0006] To achieve the above objectives, according to one aspect of this disclosure, a back-contact solar cell is provided, comprising a first region, a second region, and an isolation region disposed on the back surface of a silicon substrate. The first region and the second region are alternately disposed, and the isolation region is located between the first region and the second region. The first region includes a first doped conductive layer, and the second region includes a second doped conductive layer. The doping types of the first doped conductive layer and the second doped conductive layer are opposite. A recessed structure is provided on the side of the first region near the isolation region. When the silicon substrate is an N-type silicon substrate, the first region is a P-type doped region, and the second region is an N-type doped region. The P-type doped region has n1 recessed structures on the side near the isolation region, and the N-type doped region has n2 recessed structures on the side near the isolation region, where n1 > n2.

[0007] In some embodiments, the first region has a discontinuous recessed structure on the side near the isolation zone; and / or the second region has a recessed structure on the side near the isolation zone.

[0008] In some embodiments, the second region has a discontinuous recessed structure on the side near the isolation zone.

[0009] In some embodiments, the recessed structure includes a first unit region and a first recessed structure, the first unit region being disposed around the first recessed structure, the first recessed structure including a pit and a protrusion disposed within the pit; or the first region includes an extension portion extending and protruding above the isolation area, the recessed structure including a second unit region and a second recessed structure, the second unit region being disposed around the second recessed structure, the extension portion being provided with the second recessed structure, the second recessed structure being a blind hole or a perforation.

[0010] In some embodiments, the height of the protrusion is less than or equal to the depth of the pit; or the shape of the protrusion includes a pyramidal and / or frustum-shaped shape; or the silicon substrate has a light-facing surface disposed opposite to the backlight surface, and along the direction of the light-facing surface toward the backlight surface, the protrusion includes the silicon substrate and a passivation layer, and the sidewall of the pit includes the passivation layer.

[0011] In some embodiments, the width of the bottom of the protrusion is 0.1 μm to 1.5 μm, and the height of the protrusion is 0.01 μm to 10 μm;

[0012] In some embodiments, the width of the opening of the pit is 0.1 μm to 2 μm, and the depth of the pit is 0.01 μm to 10 μm.

[0013] In some embodiments, the passivation layer of the back contact solar cell surrounds the extension portion, and the second recessed structure penetrates the extension portion and the passivation layer; or the width of the second recessed structure is 0.1 μm to 1.5 μm.

[0014] In some embodiments, a plurality of the recessed structures form an isolation transition region, the width of which is 5 μm to 30 μm.

[0015] In some embodiments, the width of the isolation transition zone is 10 μm to 15 μm.

[0016] In some embodiments, the tunneling layer of the back contact solar cell includes a first tunneling layer disposed between the silicon substrate and the first region, wherein the edges of the first doped conductive layer, the first tunneling layer, and the silicon substrate of the first region all extend toward the center of the opening of the isolation region to form the extension portion, or only the first doped conductive layer extends toward the center of the opening of the isolation region to form the extension portion; and or, the tunneling layer of the back contact solar cell further includes a second tunneling layer disposed between the second doped conductive layer and the silicon substrate of the second region; or the passivation layer of the back contact solar cell covers the first doped conductive layer, the second doped conductive layer, and the isolation region, and the back contact solar cell further includes a first electrode and a second electrode, wherein the first electrode passes through the passivation layer and is connected to the first doped conductive layer, and the second electrode passes through the passivation layer and is connected to the second doped conductive layer.

[0017] In some embodiments, the second recessed structure is a blind hole or a perforation; or the diameter of the second recessed structure is 1.5 μm to 5 μm; or the length of the extended portion is 0.1 μm to 40 μm.

[0018] In some embodiments, the side of the first region near the isolation zone includes a first target region, the length of the first target region along the extension direction of the isolation zone is greater than 50 μm, and the first target region does not include the recessed structure; the side of the second region near the isolation zone includes a second target region, the length of the second target region along the extension direction of the isolation zone is greater than 50 μm, and the second target region does not include the recessed structure.

[0019] According to another aspect of this disclosure, a back-contact solar cell is provided, comprising: a silicon substrate having opposing light-facing and back-facing surfaces, the back-facing surface including alternating first and second regions along a first direction, both the first and second regions extending along a third direction intersecting the first direction; a plurality of first doped conductive layers disposed on the first regions and covering at least a portion of the first regions, each of the first regions having a first doped conductive layer, and at least a portion of the first doped conductive layers having a first recessed structure formed thereon; and a plurality of second doped conductive layers disposed on second regions and covering at least a portion of the second regions, each of the second regions having a second doped conductive layer, at least a portion of the second doped conductive layers having a leakage contact portion extending to the first doped conductive layer, and the leakage contact portion partially extending into the first recessed structure, the leakage contact portion making leakage contact with the first doped conductive layer at least within the first recessed structure.

[0020] In some embodiments, the leakage contact includes a first portion located within the first recessed structure and a second portion stacked on the surface of the first doped conductive layer facing away from the silicon substrate. The first portion makes leakage contact with the first doped conductive layer, and an insulating dielectric layer is provided between the second portion and the first doped conductive layer. Alternatively, the second portion makes leakage contact with the surface of the first doped conductive layer facing away from the silicon substrate. Or, in the first direction, the leakage contact extends along the side of the first doped conductive layer to the surface of the first doped conductive layer facing away from the silicon substrate and into the first recessed structure. The leakage contact also forms leakage contact with the first doped conductive layer at the side of the first doped conductive layer. Or, in the first direction, there is a first predetermined distance between the first recessed structure and the side of the first doped conductive layer, the magnitude of which is 10 μm to 200 μm. Or, in the first direction, the length of the first recessed structure is 10 μm to 80 μm, and / or in the third direction, the length of the first recessed structure is less than 10 μm to 500 μm.

[0021] In some embodiments, the ratio between the length of the first recessed structure in the third direction and the length of the first recessed structure in the first direction is greater than or equal to 2.

[0022] In some embodiments, the first doped conductive layer has opposing first and second sides in the first direction, the first recessed structure does not penetrate the first and second sides, and the first doped conductive layer is present on both sides of the first recessed structure in the first direction; or the first doped conductive layer has opposing first and second sides in the first direction, and the first recessed structure penetrates at least one of the first and second sides; or the first recessed structure completely penetrates the first doped conductive layer in the thickness direction of the first doped conductive layer, so that the silicon substrate is exposed at the first recessed structure, and the leakage contact covers the silicon substrate exposed from the first recessed structure and at least a portion of the sidewall surface of the first recessed structure; or the first recessed structure does not completely penetrate the first doped conductive layer in the thickness direction of the first doped conductive layer, and the leakage contact covers the first recessed structure. At least a portion of the bottom surface and at least a portion of the sidewall of the first recessed structure; or the first recessed structure completely penetrates the first doped conductive layer in the thickness direction and forms a trench on the silicon substrate, the recess depth of the trench in the thickness direction of the silicon substrate being 1μm to 6μm; or the first recessed structure completely penetrates the first doped conductive layer in the thickness direction and forms a trench on the silicon substrate, the first doped conductive layer on both sides of the trench having a second protrusion extending above the trench, the leakage contact portion surrounding at least one second protrusion and extending into the first recessed structure; or the first recessed structure completely penetrates the first doped conductive layer in the thickness direction and forms a trench on the silicon substrate, in the first direction, the first doped conductive layer on both sides of the trench and the edge of the trench having a second predetermined distance.

[0023] In some embodiments, an inner expansion layer is formed in a portion of the silicon substrate corresponding to the first region, and the polarity of the inner expansion layer is the same as the doping type of the first doped conductive layer; wherein, the first recessed structure does not penetrate the inner expansion layer, and the leakage contact portion makes leakage contact with the inner expansion layer away from the surface of the silicon substrate; or the first recessed structure penetrates the inner expansion layer, and the leakage contact portion makes leakage contact with the side of the inner expansion layer exposed at the first recessed structure.

[0024] In some embodiments, the second region is a groove formed on the silicon substrate, the first doped conductive layer has a first protrusion extending above the groove, the leakage contact extends along the sidewall of the groove, surrounds the first protrusion, extends onto the first doped conductive layer, and extends into the first recessed structure; or the second region is a groove formed on the silicon substrate, the first doped conductive layer does not completely cover the first region, so that the first region has an exposed area not covered by the first doped conductive layer between the first doped conductive layer and the groove, the leakage contact extends to the exposed area and covers the exposed area; or at the edge of the first doped conductive layer facing the groove, the first doped conductive layer forms a stepped structure, the leakage contact covers the stepped structure, and the leakage contact makes leakage contact with the first doped conductive layer at the stepped structure.

[0025] In some embodiments, a dielectric layer is provided on the area covered by the leakage contact in the first recessed structure, the leakage contact covering the dielectric layer, and the leakage contact making leakage contact with the first doped conductive layer through the dielectric layer within the first recessed structure.

[0026] In some embodiments, the second preset distance is 0.3 μm to 50 μm.

[0027] In some embodiments, the first recessed structure does not completely penetrate the first doped conductive layer in the thickness direction of the first doped conductive layer, and the recess depth of the first recessed structure is 20nm to 200nm; or on a single first doped conductive layer, the number of the first recessed structures is multiple, and the multiple first recessed structures are arranged at intervals in the third direction.

[0028] In some embodiments, in the third direction, the distance between two adjacent first recessed structures is 1cm-10cm; or multiple first recessed structures are arranged in at least two columns in the third direction.

[0029] In some embodiments, in the back-contact solar cell, the distribution density of the first recessed structure is 0.01 structures / cm². 2 -1.5 pieces / cm 2 Alternatively, in a single first recessed structure, the area of ​​the leakage contact portion in contact with the first doped conductive layer is 1.2 μm. 2 -1500μm 2 Alternatively, in the back-contact solar cell, the ratio of the sum of the areas of all the leakage contacts and the leakage contacts of the first doped conductive layer to the back surface area of ​​the back-contact solar cell is 4.5 * 10. -8-1.5*10 -5 .

[0030] In some embodiments, the regions in the first doped conductive layer and the second doped conductive layer not covered by the leakage contact portion are non-leakage regions, and the regions in the first doped conductive layer and the second doped conductive layer other than the non-leakage regions are leakage regions; within the same unit length, the number of the first recessed structures in the non-leakage regions is greater than the number of the first recessed structures in the leakage regions.

[0031] According to another aspect of this disclosure, a photovoltaic module is provided, including any of the back-contact solar cells described above.

[0032] According to another aspect of this disclosure, a photovoltaic system is provided, including the photovoltaic module as described above.

[0033] Implementing this disclosure will have the following beneficial effects:

[0034] 1. This invention provides a recessed structure on the side of the backlight surface of the back contact battery near the isolation region in the first region, thereby improving the isolation effect of the isolation region on the first region and the second region. Furthermore, the recessed structure increases the contact area between the first region and the subsequently grown passivation layer, thus improving the passivation effect.

[0035] 2. In this invention, a recessed structure is provided on the side of the second region of the backlight surface of the back contact battery near the isolation region, thereby improving the isolation effect of the isolation region on the first and second regions. Furthermore, the recessed structure increases the contact area between the second region and the subsequently grown passivation layer, thus improving the passivation effect.

[0036] 3. The first recessed structure of the present invention includes a pit and a protrusion disposed in the pit. The bottom of the pit is formed on the silicon substrate, which can improve the isolation effect between the first region and the second region. The protrusion further increases the contact area with the subsequently deposited passivation layer, and the overall passivation performance is further improved.

[0037] 4. The first region of the present invention has an extension portion extending and protruding above the isolation region at the edge of the isolation region, thereby forming an isolation region with a small opening and a large interior, reducing the exchange of plasma with the outside world during the subsequent deposition of the passivation layer; a second recessed structure is provided in the extension portion, the second recessed structure penetrates the extension portion, and increases the isolation and passivation performance of the extension portion. Attached Figure Description

[0038] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure. In the drawings:

[0039] Figure 1 is a schematic diagram of the first structure of the back-contact solar cell provided in this disclosure;

[0040] Figure 2 is a 3D micrograph of the back surface of the back contact solar cell provided in this disclosure;

[0041] Figure 3 is a schematic diagram of the first recessed structure provided in an embodiment of this disclosure;

[0042] Figure 4 is a schematic diagram of the dimensions of the first recessed structure provided in an embodiment of this disclosure;

[0043] Figure 5 is a schematic diagram of the second recessed structure provided in an embodiment of this disclosure;

[0044] Figure 6 is an electron microscope image of the recessed structure provided in an embodiment of this disclosure;

[0045] Figure 7 is an electron microscope image of the first recessed structure provided in an embodiment of this disclosure;

[0046] Figure 8 is a schematic diagram of a second structure of the back-contact solar cell provided in this disclosure;

[0047] Figure 9 is a schematic diagram of the structure of an extension portion of a back-contact solar cell provided in this disclosure having a second recessed structure;

[0048] Figure 10 is a schematic diagram of the structure of another embodiment of the back contact solar cell provided in this disclosure, in which the extended portion has a second recessed structure.

[0049] Figure 11 is an enlarged structural diagram of the hole portion in Figure 10;

[0050] Figure 12 is a schematic diagram of an embodiment of the back contact solar cell provided in this disclosure, in which the first region, the first tunneling layer and the first doped conductive layer are all provided with extended portions.

[0051] Figure 13 is a schematic diagram of the microstructure of another embodiment of the back contact solar cell provided in this disclosure, in which the first region, the first tunneling layer and the first doped conductive layer are all provided with extended portions.

[0052] Figure 14 is a schematic diagram of a back-contact solar cell embodiment provided in this disclosure, in which only the first doped conductive layer has an extended portion.

[0053] Figure 15 is a schematic diagram of the microstructure of an embodiment of the back contact solar cell provided in this disclosure, in which only the first doped conductive layer is provided with an extended portion.

[0054] Figure 16 is a schematic diagram of another embodiment of the back contact solar cell provided in this disclosure, in which only the first doped conductive layer has an extended portion.

[0055] Figure 17 is a schematic diagram of the microstructure of another embodiment of the back contact solar cell provided in this disclosure, in which only the first doped conductive layer is provided with an extended portion.

[0056] Figure 18 is a schematic diagram of the modules of the photovoltaic system provided in an embodiment of this disclosure;

[0057] Figure 19 is a schematic diagram of a battery assembly provided in an embodiment of this disclosure;

[0058] Figure 20 is a schematic diagram of a planar structure of a back-contact solar cell provided in an embodiment of this disclosure;

[0059] Figure 21 is a schematic cross-sectional view of the back-contact solar cell along line IV-IV in Figure 20;

[0060] Figure 22 is another cross-sectional schematic diagram of the back-contact solar cell provided in an embodiment of the present disclosure;

[0061] Figure 23 is another cross-sectional schematic diagram of the back-contact solar cell provided in an embodiment of this disclosure;

[0062] Figure 24 is a schematic diagram of the arrangement and structure of the first recessed structure in the back contact solar cell provided in an embodiment of the present disclosure;

[0063] Figure 25 is a schematic diagram of another planar structure of the back-contact solar cell provided in an embodiment of this disclosure;

[0064] Figure 26 is a schematic diagram of another arrangement and structure of the first recessed structure in the back contact solar cell provided in an embodiment of the present disclosure;

[0065] Figure 27 is another cross-sectional schematic diagram of the back-contact solar cell provided in the embodiment of this disclosure;

[0066] Figure 28 is another cross-sectional schematic diagram of the back-contact solar cell provided in the embodiments of this disclosure;

[0067] Figure 29 is another cross-sectional schematic diagram of the back-contact solar cell provided in the embodiments of this disclosure;

[0068] Figure 30 is another cross-sectional schematic diagram of the back-contact solar cell provided in the embodiments of this disclosure;

[0069] Figure 31 is another cross-sectional schematic diagram of the back-contact solar cell provided in an embodiment of the present disclosure. Detailed Implementation

[0070] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0071] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0072] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0073] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.

[0074] As described in the background section, in the prior art, when external obstructions block the back-contact solar cells during use, hot spots appear on the blocked cells. At high temperatures, this can easily lead to carbonization of the encapsulation film and even cause a fire. To address at least one of the following problems in the prior art: poor hot spot resistance, poor isolation performance of different doped regions on the back surface of the back-contact solar cell, low photoelectric conversion efficiency of the solar cell, low performance of the back-contact solar cell, and easy identification confusion, embodiments of this disclosure provide a back-contact solar cell, a photovoltaic module, and a photovoltaic system. The back-contact solar cell includes a first region and a second region disposed on the back surface of a silicon substrate, with the first and second regions alternately arranged. The first region includes a first doped conductive layer, and the second region includes a second doped conductive layer. The doping types of the first and second doped conductive layers are opposite.

[0075] The technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings.

[0076] In some optional embodiments, a back-contact solar cell includes a first region and a second region disposed on the back surface of a silicon substrate, the first region and the second region being alternately disposed. The first region includes a first doped conductive layer, and the second region includes a second doped conductive layer. The doping types of the first doped conductive layer and the second doped conductive layer are opposite. The back-contact solar cell also includes an isolation region located between the first region and the second region. A recessed structure is provided on the side of the first region near the isolation region.

[0077] Referring to Figure 1, this disclosure provides a back-contact solar cell, including a first region 13, a second region 14, and an isolation region 15 disposed on the back surface 12 of a silicon substrate 1. The first region 13 and the second region 14 are alternately disposed. The first region 13 includes a first doped conductive layer 161, and the second region 14 includes a second doped conductive layer 162. The doping types of the first doped conductive layer 161 and the second doped conductive layer 162 are opposite. Specifically, the first doped conductive layer may have the same or opposite doping type as the silicon substrate, and the second doped conductive layer may have the opposite conductivity type to the first doped conductive layer. Therefore, the back surface of the back-contact solar cell has a first region and a second region with opposite conductivity types on one side, and an isolation region is provided between the first region and the second region with opposite conductivity types. The spaced first region and the second region can prevent the first region and the second region from contacting each other and causing a short circuit.

[0078] The first area 13 has a recessed structure 17 on the side near the isolation zone 15.

[0079] Compared to existing methods that use an isolation region between the first and second regions, this disclosure further includes a recessed structure on the side of the first region closest to the isolation region. This recessed structure further enhances the isolation between the first and second regions. As battery structures shrink, the spacing between the first and second regions with different doping types is becoming increasingly smaller, placing higher demands on the isolation region between them. The recessed structure increases the isolation effect between the first and second regions while maintaining the same isolation region width. The recessed structure also improves light absorption, reduces light reflectivity, and allows more light to generate charge carriers within the silicon substrate, thus improving the photoelectric conversion efficiency of the battery. Furthermore, the recessed structure increases the contact area between the first region and the passivation layer subsequently deposited on its surface, thereby improving the passivation effect of the passivation layer on the first region and further enhancing the photoelectric conversion efficiency of the back-contact solar cell.

[0080] In a preferred embodiment, as shown in FIG2, the first region 13 has a discontinuous recessed structure 17 on the side near the isolation region 15, and several discontinuous recessed structures form an isolation transition region 171. The discontinuous distribution of the recessed structures can further improve the isolation effect of the first region and the second region. Specifically, the width L of the isolation transition region 171 can be set to 5μm to 30μm, exemplarily 6μm, 8μm, 10μm, 15μm, 20μm or 25μm, but is not limited thereto. More preferably, the width L of the isolation transition region 171 is 10μm to 15μm. By controlling the width range of the isolation transition region 171, the isolation performance is improved without adversely affecting the performance of the first region 13 and the second region 14 themselves, ensuring the collection and transport effect of charge carriers.

[0081] Correspondingly, a recessed structure can also be provided on the side of the second region near the isolation zone, and the function of the recessed structure is the same as that of the recessed structure on the side of the first region near the isolation zone. In a preferred embodiment, the side of the second region near the isolation zone has a discontinuous recessed structure. Similarly, several discontinuous recessed structures form an isolation transition zone, the width of which is 5μm to 30μm, and more preferably, the width of which is 10μm to 15μm.

[0082] Specifically, as shown in Figures 1, 3, 6, and 7, the recessed structure 17 includes a first unit region 172 and a first recessed structure 173. The first unit region 172 is disposed around the first recessed structure 173. The first recessed structure 173 includes a pit 174 and a protrusion 175 disposed within the pit 174. Specifically, the silicon substrate 1 includes a light-facing surface 11 and a backlight surface 12 disposed opposite to each other. Along the direction from the light-facing surface 11 to the backlight surface 12, the protrusion 175 includes the silicon substrate 1 and a passivation layer 18. The sidewall of the pit 174 includes the passivation layer 18. The first unit region 172 includes the silicon substrate 1, a tunneling layer 19, a doped conductive layer 16, and a passivation layer 18. The silicon substrate 1, the tunneling layer 19, the doped conductive layer 16, and the passivation layer 18 are sequentially stacked. It should be noted that, in the first region 13, the doped conductive layer 16 included in the first unit region 172 is a first doped conductive layer 161, and in the second region 14, the doped conductive layer 16 included in the first unit region 172 is a second doped conductive layer 162. By forming a first recessed structure 173 in the first region 13 and / or the second region 14, with the bottom of the pit 174 of the first recessed structure 173 set to the silicon substrate 1, the isolation effect of the first region 13 and the second region 14 can be improved. Then, a passivation layer 18 is covered on top of the first recessed structure 173, and the setting of the protrusion 175 further increases the contact area between the passivation layer 18 and the first region 13 and / or the second region 14, thereby further improving the overall passivation performance.

[0083] The passivation layer 18 reduces the recombination of surface carriers. The passivation layer 18 covers the first region 13, the second region 14, and the isolation region 15. The passivation layer 18 passivates the side of the first doped conductive layer 161 and the second doped conductive layer 162 facing away from the silicon substrate 1, reducing the carrier recombination rate on this side and further improving the photoelectric conversion efficiency of the back-contact solar cell. The passivation layer 18 can be one or more of an aluminum oxide layer, a silicon nitride layer, a silicon oxide layer, and a silicon oxynitride layer. Preferably, the passivation layer 18 comprises an aluminum oxide layer and a silicon nitride layer stacked sequentially.

[0084] The tunneling layer can be divided into a first tunneling layer and a second tunneling layer. The first tunneling layer is disposed between the silicon substrate and the first doped conductive layer in the first region; the second tunneling layer is disposed between the silicon substrate and the second doped conductive layer in the second region. The tunneling layer allows majority carriers to tunnel into the doped conductive layer while blocking minority carriers from passing through. Thus, the majority carriers are transported via the first and second doped conductive layers and collected by the corresponding electrodes, reducing the recombination rate of carriers of different conductivity types at the surface of the first or second region. This achieves excellent selective collection of carriers and further improves the photoelectric conversion efficiency of the back-contact solar cell. The first and second tunneling layers can be one or more of silicon oxide, silicon carbide, silicon nitride, and aluminum oxide layers; preferably, the first and second tunneling layers are silicon oxide layers.

[0085] In a preferred embodiment, the height of the protrusion is less than or equal to the depth of the pit. More preferably, the height of the protrusion is less than the depth of the pit, which facilitates the subsequent deposition of the passivation layer. Specifically, the shape of the protrusion can be pyramidal and / or frustum-shaped.

[0086] Understandably, the dimensions of the bumps and pits also affect the isolation effect and passivation performance. As shown in Figure 4, the width D1 of the bottom of the bump is 0.1 μm to 1.5 μm, and the height H1 is 0.01 μm to 10 μm. If H1 < 0.01 μm, it is easy to cause short circuits and reduce yield; if H1 > 10 μm, it will affect the coverage of the subsequent passivation layer, thus reducing the passivation effect. The width D2 of the pit opening is 0.1 μm to 2 μm, and the depth H2 of the pit is 0.01 μm to 10 μm. If D2 < 0.1 μm, it affects the passivation effect; if D2 > 10 μm, copper residue will affect the passivation effect, causing leakage. Both excessively large and small H2 will affect the passivation effect. If H2 < 0.01 μm, it will weaken the hydrogen passivation of the silicon substrate by the subsequently deposited passivation layer, reducing yield; if H2 > 10 μm, it will increase the recombination of charge carriers on the silicon substrate surface. By limiting the size of the protrusions and pits, the passivation and isolation performance of the battery can be improved without adversely affecting the collection and transport of charge carriers. Moreover, controlling the size of the pits and protrusions within the scope of this disclosure is beneficial for the subsequent formation of the back passivation layer. The passivation layer can completely fill the first recessed structure, thereby improving the film quality of the passivation layer.

[0087] As shown in Figures 1, 5, and 6, the first region 13 includes an extension 163 that protrudes above the isolation region 15; the recessed structure 17 includes a second unit region 176 and a second recessed structure 177, with the second unit region 176 surrounding the second recessed structure 177. The extension 163 has the second recessed structure 177, which can be a blind hole or a perforation. For example, as shown in Figures 5 and 6, the second recessed structure 177 penetrates the extension 163, forming a hole 178; that is, in this example, the second recessed structure 177 is a perforation (hole 178).

[0088] In a preferred embodiment, as shown in FIG5, the back-contact solar cell includes a passivation layer 18 surrounding an extension portion 163, and a second recessed structure 177 penetrating the extension portion 163 and the passivation layer 18 to form a hole 178. The passivation layer 18 surrounding the extension portion 163 further ensures passivation performance. In one embodiment, the width D3 of the hole 178 is 0.1 μm to 1.5 μm, exemplary values ​​are 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 1.1 μm, or 1.4 μm, but is not limited thereto.

[0089] In addition to the above structure, the back-contact solar cell also includes a front passivation layer, a first electrode, and a second electrode. The front passivation layer is stacked on the front side of the silicon substrate, where there is no obstruction from metal electrodes. The first electrode penetrates the passivation layer and contacts the first doped conductive layer, and the second electrode penetrates the passivation layer and contacts the second doped conductive layer. The materials of the first and second electrodes can be one or more of silver, aluminum, copper, and nickel.

[0090] In a preferred embodiment, the number of recessed structures on the side of the doped region with a different doping type from the silicon substrate is greater than or equal to the number on the side with the same doping type as the silicon substrate. This improves the conductivity of the chemical solution in subsequent processes, facilitates the cleaning of impurities such as metals, and thus improves the surface quality of the recessed structures. Furthermore, a greater number of recessed structures on the emitter side is beneficial for current collection. It is understood that when the silicon substrate is a P-type silicon substrate, the first doped region is an N-type doped region, and the second doped region is a P-type doped region. The P-type doped region has n1 recessed structures on the side near the isolation region, and the N-type doped region has n2 recessed structures on the side near the isolation region, where n1 ≤ n2, and preferably, n1 < n2. That is, when the silicon substrate is a P-type silicon substrate, the number of recessed structures on the side of the P-type doped region near the isolation region is less than or equal to the number on the side of the N-type doped region. Further, when the silicon substrate is a P-type silicon substrate, n1 can be 0.

[0091] Accordingly, when the silicon substrate is an N-type silicon substrate, the first doped region is a P-type doped region, and the second doped region is an N-type doped region. The P-type doped region has n1 recessed structures on the side near the isolation region, and the N-type doped region has n2 recessed structures on the side near the isolation region, where n1 ≥ n2, and preferably, n1 > n2. That is, when the silicon substrate is an N-type silicon substrate, the number of recessed structures on the side of the P-type doped region near the isolation region is greater than or equal to the number on the side of the N-type doped region. Since the P-type doped region is the emitter, providing more recessed structures in the P-type doped region is beneficial for current collection. Further, when the silicon substrate is an N-type silicon substrate, n2 can be 0.

[0092] Optionally, in order to facilitate the transport and collection of charge carriers and reduce the risk of stress defects and microcracks in the solar cell, the spacing between two adjacent recessed structures 17 on the side of the first region 13 near the isolation region 15 is greater than 100 μm; and / or, the spacing between two adjacent recessed structures 17 on the side of the second region 14 near the isolation region 15 is greater than 100 μm.

[0093] Optionally, the first region includes a first target region on the side near the isolation zone, the first target region having a length greater than 50 μm along the extension direction of the isolation zone, and the first target region does not include a recessed structure; the second region includes a second target region on the side near the isolation zone, the second target region having a length greater than 50 μm along the extension direction of the isolation zone, and the second target region does not include a recessed structure.

[0094] Accordingly, this disclosure also provides a method for fabricating the above-mentioned back-contact solar cell, comprising:

[0095] S1. Provide a silicon substrate;

[0096] Specifically, the silicon substrate can be an N-type silicon substrate or a P-type silicon substrate, and the backlight surface of the silicon substrate has an alternately arranged first region and a second region.

[0097] S2. A first doped conductive layer is formed in at least a first region of the backlight surface of the silicon substrate, and a recessed structure is formed on the surface of the first region.

[0098] The first doped conductive layer can be disposed inside or on the silicon substrate. Preferably, the first tunneling layer and the first doped conductive layer are disposed in a first region on the backlight surface of the silicon substrate. The first doped conductive layer can be a P-type doped conductive layer or an N-type doped conductive layer.

[0099] In a preferred embodiment, a first tunneling layer and a first doped conductive layer are formed on the back surface of a silicon substrate. At least the portion of the first tunneling layer located in the second region is processed to remove at least the portion of the first tunneling layer located in the second region. The processing employs laser direct etching and wet etching. After processing, a recessed structure is formed on the surface of the first doped conductive layer.

[0100] S3. At least a second doped conductive layer is formed in the second region;

[0101] The second doped conductive layer can be disposed within or on the silicon substrate. Preferably, the second tunneling layer and the second doped conductive layer are disposed in a second region on the backlight surface of the silicon substrate, and the doping type of the second doped conductive layer is opposite to that of the first doped conductive layer.

[0102] In a preferred embodiment, a second tunneling layer and a second doped conductive layer are formed on the back surface of a silicon substrate and on a first doped conductive layer. At least the portion of the second tunneling layer located on the first doped conductive layer is processed to at least remove the portion of the second tunneling layer located on the first doped conductive layer. The processing is performed by laser direct etching and wet etching. After processing, a recessed structure is formed on the surface of the first doped conductive layer.

[0103] S4. An isolation zone is formed between the first and second zones.

[0104] In a preferred embodiment, the portion of the second tunneling layer located between the first and second regions is processed to remove the portion of the second tunneling layer located between the first and second regions, forming an isolation region. The processing employs laser direct etching and wet etching, and after processing, a recessed structure is formed on the surface of the second doped conductive layer.

[0105] Subsequently, a passivation layer is deposited on the first doped conductive layer, the second doped conductive layer, and the isolation region to form a first electrode in contact with the first doped conductive layer and a second electrode in contact with the second doped conductive layer.

[0106] The present disclosure will be further described below with reference to specific embodiments:

[0107] Example 1

[0108] This embodiment provides a back-contact solar cell, including a P-type doped region, an N-type doped region, and an isolation region disposed on the back side of an N-type silicon substrate. The P-type and N-type doped regions are alternately arranged, and the isolation region is located between the P-type and N-type doped regions. The P-type doped regions include a P-type doped conductive layer, and the N-type doped regions include an N-type doped conductive layer. A recessed structure is provided on the side of the P-type doped region near the isolation region.

[0109] The recessed structure includes a first recessed structure and a first unit region surrounding the first recessed structure. The first recessed structure includes a pit and a protrusion disposed within the pit. Specifically, along the direction from the light-facing surface of the silicon substrate to the backlight-facing surface, the protrusion includes a silicon substrate and a passivation layer. The sidewalls of the pit include a passivation layer. The first unit region includes a silicon substrate, a tunneling layer, a P-type doped conductive layer, and a passivation layer stacked sequentially. The width of the bottom of the protrusion is 0.1 μm to 1.5 μm, the height of the protrusion is 0.01 μm to 10 μm, the width of the pit opening is 0.1 μm to 2 μm, the depth of the pit is 0.01 μm to 10 μm, and the shape of the protrusion is pyramidal.

[0110] Example 2

[0111] This embodiment provides a back-contact solar cell, including a P-type doped region, an N-type doped region, and an isolation region disposed on the back side of an N-type silicon substrate. The P-type and N-type doped regions are alternately arranged, and the isolation region is located between the P-type and N-type doped regions. The P-type doped regions include a P-type doped conductive layer, and the N-type doped regions include an N-type doped conductive layer. A recessed structure is provided on the side of the P-type doped region near the isolation region.

[0112] The recessed structure includes a first recessed structure and a first unit region surrounding the first recessed structure. The first recessed structure includes a pit and a protrusion disposed within the pit. Specifically, along the direction from the light-facing surface of the silicon substrate to the backlight-facing surface, the protrusion includes a silicon substrate and a passivation layer, the sidewalls of the pit include a passivation layer, and the first unit region includes a silicon substrate, a tunneling layer, a P-type doped conductive layer, and a passivation layer stacked sequentially. The width of the bottom of the protrusion is 0.3 μm to 1.2 μm, the height of the protrusion is 0.05 μm to 2 μm, the width of the pit opening is 0.5 μm to 2 μm, the depth of the pit is 0.1 μm to 5 μm, and the shape of the protrusion is pyramidal.

[0113] Example 3

[0114] This embodiment provides a back-contact solar cell, including a P-type doped region, an N-type doped region, and an isolation region disposed on the back side of an N-type silicon substrate. The P-type and N-type doped regions are alternately arranged, and the isolation region is located between the P-type and N-type doped regions. The P-type doped regions include a P-type doped conductive layer, and the N-type doped regions include an N-type doped conductive layer. A recessed structure is provided on the side of the P-type doped region near the isolation region.

[0115] The recessed structure includes a first recessed structure and a first unit region surrounding the first recessed structure. The first recessed structure includes a pit and a protrusion disposed within the pit. Specifically, along the direction from the light-facing surface of the silicon substrate to the backlight-facing surface, the protrusion includes a silicon substrate and a passivation layer, the sidewalls of the pit include a passivation layer, and the first unit region includes a silicon substrate, a tunneling layer, a P-type doped conductive layer, and a passivation layer stacked sequentially. The width of the bottom of the protrusion is 0.3 μm to 1.2 μm, the height of the protrusion is 0.05 μm to 2 μm, the width of the pit opening is 0.5 μm to 2 μm, the depth of the pit is 0.1 μm to 5 μm, and the shape of the protrusion is pyramidal.

[0116] The P-type doped region includes an extension that protrudes above the isolation region. The recessed structure also includes a second recessed structure and a second unit region surrounding the second recessed structure. The second recessed structure penetrates the extension to form a hole with a width of 0.1 μm to 1.5 μm.

[0117] Example 4

[0118] This embodiment provides a back-contact solar cell, including a P-type doped region, an N-type doped region, and an isolation region disposed on the back side of an N-type silicon substrate. The P-type and N-type doped regions are alternately arranged, and the isolation region is located between the P-type and N-type doped regions. The P-type doped regions include a P-type doped conductive layer, and the N-type doped regions include an N-type doped conductive layer. A recessed structure is provided on the side of the P-type doped region near the isolation region.

[0119] The recessed structure includes a first recessed structure and a first unit region surrounding the first recessed structure. The first recessed structure includes a pit and a protrusion disposed within the pit. Specifically, along the direction from the light-facing surface of the silicon substrate to the backlight-facing surface, the protrusion includes a silicon substrate and a passivation layer, the sidewalls of the pit include a passivation layer, and the first unit region includes a silicon substrate, a tunneling layer, a P-type doped conductive layer, and a passivation layer stacked sequentially. The width of the bottom of the protrusion is 0.3 μm to 1.2 μm, the height of the protrusion is 0.05 μm to 2 μm, the width of the pit opening is 0.5 μm to 2 μm, the depth of the pit is 0.1 μm to 5 μm, and the shape of the protrusion is pyramidal.

[0120] The P-type doped region includes an extension that protrudes above the isolation region. The recessed structure also includes a second recessed structure and a second unit region surrounding the second recessed structure. The second recessed structure penetrates the extension to form a hole with a width of 0.5 μm to 0.8 μm.

[0121] Example 5

[0122] This embodiment provides a back-contact solar cell, including a P-type doped region, an N-type doped region, and an isolation region disposed on the back side of an N-type silicon substrate. The P-type doped region and the N-type doped region are alternately disposed, and the isolation region is located between the P-type doped region and the N-type doped region. The P-type doped region includes a P-type doped conductive layer, and the N-type doped region includes an N-type doped conductive layer.

[0123] The P-type doped region has a recessed structure on the side near the isolation region.

[0124] The recessed structure includes a first recessed structure and a first unit region surrounding the first recessed structure. The first recessed structure includes a pit and a protrusion disposed within the pit. Specifically, along the direction from the light-facing surface of the silicon substrate to the backlight-facing surface, the protrusion includes a silicon substrate and a passivation layer, the sidewalls of the pit include a passivation layer, and the first unit region includes a silicon substrate, a tunneling layer, a P-type doped conductive layer, and a passivation layer stacked sequentially. The width of the bottom of the protrusion is 0.3 μm to 1.2 μm, the height of the protrusion is 0.05 μm to 2 μm, the width of the pit opening is 0.5 μm to 2 μm, the depth of the pit is 0.1 μm to 5 μm, and the shape of the protrusion is pyramidal.

[0125] The P-type doped region includes an extension that protrudes above the isolation region. The recessed structure also includes a second recessed structure and a second unit region surrounding the second recessed structure. The second recessed structure penetrates the extension to form a hole with a width of 0.5 μm to 0.8 μm.

[0126] A first recessed structure is also provided on the side of the N-type doped region near the isolation region. The number of first recessed structures in the N-type doped region is less than the number of first recessed structures in the P-type doped region. Everything else is the same as in Example 1.

[0127] The back-contact solar cell printed electrodes prepared in Examples 1 to 5 were sintered and then annealed to obtain finished solar cell wafers. The photoelectric conversion efficiency of the finished solar cell wafers was measured, and the results are shown in the table below.

[0128] The back-contact solar cell disclosed herein includes a silicon substrate, a first tunneling layer, and a first doped conductive layer. The silicon substrate has a front side and a back side facing each other. The back side is provided with a plurality of first regions and second regions arranged alternately along a first direction. Adjacent first regions and second regions are separated by an isolation trench. The first doped conductive layer is disposed on the silicon substrate of the first region. The first tunneling layer is disposed between the first doped conductive layer and the silicon substrate of the first region. The edges of the first doped conductive layer, the tunneling layer, and the silicon substrate of the first region all extend toward the opening center of the isolation trench to form an extension portion, or only the first doped conductive layer extends toward the opening center of the isolation trench to form an extension portion. The extension portion is provided with a second recessed structure. By setting an extension section to reduce the opening of the isolation trench, the exchange between plasma and the outside environment can be reduced during the subsequent deposition of the passivation layer. This allows for a localized distribution of hydrogen content in the passivation layer, resulting in lower mobile oxygen content in the passivation layer within the isolation trench and higher mobile oxygen content in the passivation film layer in other areas. This effectively improves passivation and anti-attenuation effects. In addition, by setting a second recessed structure in the extension section, it is beneficial for identification and alignment in subsequent processes without affecting the passivation polycrystalline silicon film, thus ensuring the conversion efficiency of the solar cell.

[0129] Example 6

[0130] As shown in Figures 8 to 17, one embodiment of this disclosure provides a back-contact solar cell, including a silicon substrate 1. The silicon substrate 1 has a light-facing surface 11 and a back-light-facing surface 12. The back-light-facing surface 12 is provided with a plurality of first regions 13 and second regions 14 arranged alternately along a first direction. Adjacent first regions 13 and second regions 14 are separated by an isolation region 15.

[0131] A first doped conductive layer 161 is disposed on a silicon substrate 1 in the first region 13; and a first tunneling layer 200 is disposed between the first doped conductive layer 161 and the silicon substrate 1 in the first region 13.

[0132] The edges of the first doped conductive layer 161, the first tunneling layer 200, and the silicon substrate 1 of the first region 13 all extend toward the center of the opening of the isolation region 15 to form an extension portion, or only the first doped conductive layer 161 extends toward the center of the opening of the isolation region 15 to form an extension portion.

[0133] The extended portion is provided with a second recessed structure 177.

[0134] The silicon substrate 1 is in the form of a sheet or plate, and the silicon substrate 1 has a light-facing surface 11 and a back-light-facing surface 12, which are usually...

[0135] Optionally, the silicon substrate 1 can be either an N-type silicon wafer or a P-type silicon wafer, without limitation. An N-type silicon wafer refers to an intrinsic semiconductor doped with a pentavalent element (such as phosphorus, arsenic, or bismuth), while a P-type silicon wafer refers to an intrinsic semiconductor doped with a trivalent element (such as boron, gallium, or indium), without further explanation.

[0136] In practice, the backlight surface 12 of the silicon substrate 1 is formed with a plurality of isolation regions 15 arranged at intervals. The backlight surface 12 is divided into a plurality of first regions 13 and second regions 14 arranged alternately through the isolation regions 15. That is, adjacent first regions 13 and second regions 14 are separated by the isolation regions 15.

[0137] In some alternative embodiments, the first direction is a horizontal lateral direction, as shown in FIG8. The extension direction of line segment L is the first direction. The first region 13 and the second region 14 are alternately arranged along the horizontal lateral direction of the silicon substrate 1, and the isolation region 15 extends along the longitudinal direction to separate the adjacent first region 13 and second region 14.

[0138] In implementation, the first region 13 and the second region 14 are regions with opposite doping types in the solar cell. For example, taking an N-type silicon wafer as the silicon substrate 1, doping the N-type silicon wafer with a trivalent element yields the emitter region, which can be considered a p+ layer. Similarly, doping the N-type silicon wafer with a pentavalent element yields the doped diffusion layer, which can be considered an n+ layer. When the first region 13 is a p+ layer, the second region 14 is an n+ layer; conversely, when the first region 13 is an n+ layer, the second region 14 is a p+ layer.

[0139] The first tunneling layer 200 and the first doped conductive layer 161 are stacked on the first region 13. The edges of the first tunneling layer 200, the first doped conductive layer 161, and the silicon substrate 1 of the first region 13 all extend toward the center of the opening of the isolation region 15 to form an extension portion. In other words, the first tunneling layer 200, the first doped conductive layer 161, and the silicon substrate 1 of the first region 13 all protrude toward the opening of the isolation region 15 to form an extension portion, so that the isolation region 15 forms a recessed structure with a small opening and a large interior.

[0140] In practice, the isolation area 15 and the extended portion on the silicon substrate 1 can be formed by a combination of grooving and etching. For example, an opening extending in a second direction is first formed on the silicon substrate 1 by mechanical or chemical etching, the second direction being perpendicular to the first direction, and then the opening is etched by acid etching or alkaline etching. Because the corrosion resistance of the first tunneling layer 200 and the first doped conductive layer 161 differs from that of the silicon substrate 1, typically the first tunneling layer 200 and the first doped conductive layer 161 exhibit superior corrosion resistance compared to the silicon substrate 1. This results in rapid etching of the silicon substrate 1 during acid or alkaline etching of the opening, while the first tunneling layer 200 and the first doped conductive layer 161 are etched slowly or not at all. Consequently, the etching rate of the portion of the silicon substrate 1 near the first tunneling layer 200 and the first doped conductive layer 161 decreases. This causes the edge of the silicon substrate 1 in the first region 13 near the isolation region 15 to protrude, forming a first extension 140 of the silicon substrate 1 in the first region 13. The first doped conductive layer 161 and the first tunneling layer 200 protrude from the isolation region 15, forming a second extension 310, as shown in Figure 8. By forming an isolation region 15 with a small opening and a large interior, the exchange of plasma with the external environment during subsequent passivation film deposition is reduced. It is understood that in this embodiment, the extension portions formed by the edges of the first doped conductive layer 161, the first tunneling layer 200, and the silicon substrate 1 of the first region 13 extending toward the center of the opening of the isolation region 15 include the first extension portion 140 and the second extension portion 310 shown in FIG8.

[0141] In some embodiments, when the silicon substrate 1 is acid-etched or alkaline-etched, the silicon substrate 1 is etched rapidly, while the etching rate of the portion of the silicon substrate 1 near the first tunneling layer 200 and the first doped conductive layer 161 decreases, causing the sidewall of the silicon substrate 1 in the first region 13 to form an inclined wall to form a first extension 140, and the first tunneling layer 200 and the first doped conductive layer 161 to protrude near the edge of the isolation region 15 to form a second extension 310, as shown in Figures 12 and 13, thereby forming a recessed structure with a small opening and a large interior.

[0142] In some possible embodiments, only the first doped conductive layer 161 may have a second extension 310. For example, an opening extending in the second direction may be formed on the silicon substrate 1 by mechanical or chemical etching, and then the opening may be etched by acid etching or alkaline etching. In this case, the sidewalls of the silicon substrate 1 in the first region 13 are vertical walls, and the first tunneling layer 200 and the first doped conductive layer 161 protrude near the isolation region 15. Then, the protruding first tunneling layer 200 is washed away by a subsequent cleaning process, leaving only the protruding portion of the first doped conductive layer 161. That is, only the first doped conductive layer 161 extends towards the center of the opening in the isolation region 15 to form the second extension 310, thereby forming a recessed structure with a small opening and a large interior, as shown in Figures 14 and 15. It is understood that in this embodiment, only the extension formed by the first doped conductive layer 161 extending towards the center of the opening in the isolation region 15 is the second extension 310 shown in Figures 14 and 15.

[0143] Optionally, the extended portion will make the isolation region 15 a recessed structure with a small opening and a large interior. Therefore, the length of the extended portion needs to be controlled within a certain reasonable range. For example, the length of the extended portion can be designed to be from 0.1 micrometers to 40 micrometers, such as 0.2 micrometers, 0.3 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, or any value between 0.1 micrometers and 40 micrometers. Preferably, the length of the extended portion is from 0.5 micrometers to 20 micrometers, such as 0.6 micrometers, 0.7 micrometers, 1 micrometer, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, 10 micrometers, 11 micrometers, 15 micrometers, or any value between 0.5 micrometers and 20 micrometers, without limitation. By setting the length of the extended portion within this reasonable range, it is possible to avoid the extended portion being too short, which would prevent the effective reduction of plasma exchange with the outside environment during the passivation film deposition process. It is also possible to avoid the extended portion being too long, which would result in an opening of the isolation region 15 being too small and making the etching process too difficult. At the same time, it is also possible to avoid the extended portion being too long, which would make it prone to breakage.

[0144] As shown in Figure 14, when only the first doped conductive layer 161 is provided with the second extension 310, only the second extension 310 of the first doped conductive layer 161 is provided with a plurality of second recessed structures 177.

[0145] When the silicon substrate 1 of the first doped conductive layer 161, the first tunneling layer 200 and the first region 13 are all provided with extension portions, for example, in the structure shown in FIG8 and FIG12, the first doped conductive layer 161 and the first tunneling layer 200 have second extension portions 310, and the first region 13 has a first extension portion 140. At this time, both the second extension portion 310 and the first extension portion 140 are provided with a second recessed structure 177.

[0146] It should be noted that the above-described film layer structures with extended portions and the shapes of the extended portions are illustrative examples of embodiments of this disclosure, and not specific limitations of this disclosure. In other embodiments, other structural shapes can also be designed. For example, in some embodiments, when the silicon substrate 1 is acid-etched or alkaline-etched, the silicon substrate 1 is etched rapidly, while the etching rate of the portion of the silicon substrate 1 near the first tunneling layer 200 and the first doped conductive layer 161 decreases, causing the sidewall of the silicon substrate 1 in the first region 13 to form an inclined wall, forming a first extension 140. The portion of the first tunneling layer 200 and the first doped conductive layer 161 near the isolation region 15 protrudes and extends beyond the first extension 140. Then, the protruding first tunneling layer 200 is washed away by a subsequent cleaning process, leaving only the protruding portion of the first doped conductive layer 161 to form a second extension 310. The second recessed structure 177 is only provided in the second extension 310, as shown in Figures 16 and 17, and is not limited thereto. It is understood that in this embodiment, the extension portions formed by the edges of the first doped conductive layer 161, the first tunneling layer 200, and the silicon substrate 1 of the first region 13 extending toward the center of the opening of the isolation region 15 include the first extension portion 140 and the second extension portion 310 shown in FIG16 and FIG17.

[0147] In practice, the second recessed structure 177 is a recessed structure created by a laser when the back contact solar cell is fabricated by removing the film layer using a laser. For example, when the passivation layer or BSG (Back Surface Field Silicon Wafer) is removed by a laser, the laser etches the second recessed structure 177 into the portion of the first doped conductive layer 161 and / or the first tunneling layer 200 located at the extension.

[0148] Optionally, the diameter of the second recessed structure 177 is from 0.1 μm to 5 μm, such as 0.2 μm, 0.5 μm, 1 μm, 2 μm, 3 μm or 4 μm, etc., without limitation.

[0149] In some possible embodiments, the second recessed structure 177 is a blind hole or a through hole. The type of the second recessed structure 177 can be a blind hole or a through hole, which is specifically determined by the duration and power of laser irradiation at the location of the second recessed structure 177. For example, under a fixed power condition, the first second recessed structure 177 is irradiated by laser for a shorter duration, resulting in the first second recessed structure 177 being a blind hole, while the second second recessed structure 177 is irradiated by laser for a longer duration, resulting in the second second recessed structure 177 being a through hole. This will not be elaborated further.

[0150] During the subsequent deposition of the passivation layer, these second recessed structures 177 can further reduce the exchange between the plasma and the outside world within the isolation zone 15, thereby further improving the passivation and anti-attenuation effects.

[0151] The back-contact solar cell disclosed herein includes a silicon substrate 1, a first tunneling layer 200, and a first doped conductive layer 161. The silicon substrate 1 has a light-facing surface and a back-facing surface opposite to each other. The back-facing surface is provided with a plurality of first regions 13 and second regions 14 arranged alternately along a first direction. Adjacent first regions 13 and second regions 14 are separated by an isolation region 15. The first doped conductive layer 161 is disposed on the silicon substrate 1 of the first region 13. The first tunneling layer 200 is disposed between the first doped conductive layer 161 and the silicon substrate 1 of the first region 13. The edges of the first doped conductive layer 161, the first tunneling layer 200, and the first region 13 all extend toward the center direction of the opening of the isolation region 15 to form an extension portion, or only the first doped conductive layer 161 extends toward the center direction of the opening of the isolation region 15 to form an extension portion. The extension portion is provided with a second recessed structure 177. By setting an extension portion, the opening of the isolation region 15 is reduced, which can reduce the exchange between plasma and the outside world during the subsequent deposition of the passivation layer. This allows for a localized distribution of hydrogen content in the passivation layer, resulting in a lower mobile oxygen content in the passivation layer within the isolation region 15 and a higher mobile oxygen content in the passivation film layer in other areas. This effectively improves passivation and anti-attenuation effects. In addition, by setting a second recessed structure 177 in the extension portion, it is beneficial for identification and alignment in subsequent processes without affecting the passivation polycrystalline silicon film, thus ensuring the conversion efficiency of the solar cell.

[0152] In some possible embodiments, the back-contact solar cell provided in this disclosure further includes a second tunneling layer 400 and a second doped conductive layer 162.

[0153] The second doped conductive layer 162 is disposed on the silicon substrate 1 of the second region 14, and the second tunneling layer 400 is disposed between the second doped conductive layer 162 and the silicon substrate 1 of the second region 14.

[0154] In implementation, the first doped conductive layer 161 may be either a P-type doped layer or an N-type doped layer, and the second doped conductive layer 162 may be either a P-type doped layer or an N-type doped layer. For example, in some embodiments, the first doped conductive layer 161 may be a P-type doped layer, and the second doped conductive layer 162 may be an N-type doped layer. The first tunneling layer 200 and the second tunneling layer 400 may both be one or more combinations of tunneling oxide layers (e.g., tunneling silicon oxide layers), intrinsic silicon carbide layers, and intrinsic amorphous silicon layers, without specific limitations herein. The first tunneling layer 200 and / or the second tunneling layer 400 include at least one of an amorphous silicon layer, a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbonitride layer, a titanium oxide layer, a chromium oxide layer, and an aluminum oxide layer.

[0155] In some optional embodiments, the back-contact solar cell provided in this disclosure further includes a passivation layer 18, a first electrode 700, and a second electrode 800. The passivation layer 18 covers a first doped conductive layer 161, a second doped conductive layer 162, and an isolation region 15. The first electrode 700 passes through the passivation layer 18 and is connected to the first doped conductive layer 161. The second electrode 800 passes through the passivation layer 18 and is connected to the second doped conductive layer 162. Both the first electrode 700 and the second electrode 800 are metal electrodes.

[0156] The passivation layer 18 is a passivation antireflection film. The passivation antireflection film is used to improve the photoelectric conversion efficiency and stability of solar cells, reduce surface damage and oxidation reactions of solar cells, and extend the service life of solar cells.

[0157] Optionally, the passivation layer 18 includes at least one of an amorphous silicon layer, a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbonitride layer, a titanium oxide layer, a hafnium oxide layer, and an aluminum oxide layer, without limitation.

[0158] Optionally, the backlight surface of the silicon substrate 1 can be a polished surface or a textured surface. The textured surface can be a surface with high roughness, such as a velvet surface, to reduce light reflection, increase light absorption, change the incident angle and propagation path of light, form a light trap, and increase the density of photogenerated carriers, thereby improving the photoelectric conversion efficiency of the battery.

[0159] Example 7

[0160] In some alternative embodiments, this disclosure also provides a photovoltaic module, including a back-contact solar cell as described above.

[0161] It is understood that photovoltaic modules may also include metal frames, backsheets, photovoltaic glass, and encapsulant films (not shown in the figures). The encapsulant film can be filled between the light-facing side of the back-contact solar cell and the photovoltaic glass, between the back-facing side of the back-contact solar cell and the backsheet, or between adjacent back-contact solar cells. As a filler, the encapsulant film can be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulant film can be EVA (ethylene-vinyl acetate copolymer) or POE (polyolefin elastomer) film, and the specific choice can be made according to the actual situation, without limitation. The photovoltaic glass can cover the encapsulant film on the light-facing side of the back-contact solar cell. The photovoltaic glass can be ultra-clear glass, which has high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, the light transmittance of ultra-clear glass can reach over 92%, which can protect the back-contact solar cell without affecting its efficiency as much as possible. Meanwhile, the encapsulant film can combine photovoltaic glass and back-contact solar cells. The presence of the encapsulant film can seal, insulate, and waterproof the back-contact solar cells.

[0162] The backsheet can be attached to the film on the back side of the back contact solar cell. The backsheet can protect and support the back contact solar cell and has reliable insulation, water resistance and aging resistance. There are multiple choices for the backsheet, which can usually be tempered glass, plexiglass, aluminum alloy TPT (Tedlar / PET / Tedlar, polyvinyl fluoride composite film) composite film, etc. The specific choice can be made according to the specific situation and is not limited here.

[0163] The backsheet, back-contact solar cells, encapsulant film, and photovoltaic glass can be mounted on a metal frame. The metal frame serves as the main external support structure for the entire photovoltaic module and can provide stable support and installation for the photovoltaic module. For example, the photovoltaic module can be installed at the desired location using the metal frame.

[0164] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the structure and implementation principle of the photovoltaic module described above can be referred to the corresponding structure and implementation principle in the aforementioned Embodiment 1, and will not be repeated here.

[0165] The back-contact solar cell disclosed herein includes a silicon substrate 1, a first tunneling layer 200, and a first doped conductive layer 161. The silicon substrate 1 has a light-facing surface 11 and a back-facing surface 12 facing each other. The back-facing surface is provided with a plurality of first regions 13 and second regions 14 arranged alternately along a first direction. Adjacent first regions 13 and second regions 14 are separated by an isolation region 15. The first doped conductive layer 161 is disposed on the silicon substrate 1 of the first region 13. The first tunneling layer 200 is disposed between the first doped conductive layer 161 and the silicon substrate 1 of the first region 13. The edges of the first doped conductive layer 161, the first tunneling layer 200, and the first region 13 all extend toward the center direction of the opening of the isolation region 15 to form an extension portion, or only the first doped conductive layer 161 extends toward the center direction of the opening of the isolation region 15 to form an extension portion. The extension portion is provided with a second recessed structure 177. By setting an extension portion, the opening of the isolation region 15 is reduced, which can reduce the exchange between plasma and the outside world during the subsequent deposition of the passivation layer. This allows for a localized distribution of hydrogen content in the passivation layer, resulting in a lower mobile oxygen content in the passivation layer within the isolation region 15 and a higher mobile oxygen content in the passivation film layer in other areas. This effectively improves passivation and anti-attenuation effects. In addition, by setting a second recessed structure 177 in the extension portion, it is beneficial for identification and alignment in subsequent processes without affecting the passivation polycrystalline silicon film, thus ensuring the conversion efficiency of the solar cell.

[0166] Example 8

[0167] In some alternative embodiments, this disclosure also provides a photovoltaic system including the photovoltaic modules described above.

[0168] In practice, photovoltaic (PV) systems can be applied to PV power plants, such as ground-mounted, rooftop, and floating power plants, as well as to equipment or devices that utilize solar energy for power generation, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it's understandable that the application scenarios for PV systems are not limited to these; that is, PV systems can be applied in all areas that require solar energy for power generation. Taking a PV power grid as an example, a PV system can include PV arrays, combiner boxes, and inverters. A PV array can be a combination of multiple PV modules; for example, multiple PV modules can form multiple PV arrays. The PV arrays are connected to combiner boxes, which collect the current generated by the PV arrays. The collected current then flows through an inverter, converting it into AC power required by the mains grid before being connected to the mains grid to achieve solar power supply.

[0169] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the structure and implementation principle of the photovoltaic system described above can be referred to the corresponding structure and implementation principle in the aforementioned Embodiments 1 and 2, and will not be repeated here.

[0170] The back-contact solar cell disclosed herein includes a silicon substrate 1, a first tunneling layer 200, and a first doped conductive layer 161. The silicon substrate 1 has a light-facing surface 11 and a back-lighting surface 12 facing each other. The back-lighting surface 12 is provided with a plurality of first regions 13 and second regions 14 arranged alternately along a first direction. Adjacent first regions 13 and second regions 14 are separated by an isolation region 15. The first doped conductive layer 161 is disposed on the silicon substrate 1 of the first region 13. The first tunneling layer 200 is disposed between the first doped conductive layer 161 and the silicon substrate 1 of the first region 13. The edges of the first doped conductive layer 161, the first tunneling layer 200, and the first region 13 all extend toward the center direction of the opening of the isolation region 15 to form an extension portion, or only the first doped conductive layer 161 extends toward the center direction of the opening of the isolation region 15 to form an extension portion. The extension portion is provided with a second recessed structure 177. By setting an extension portion, the opening of the isolation region 15 is reduced, which can reduce the exchange between plasma and the outside world during the subsequent deposition of the passivation layer. This allows for a localized distribution of hydrogen content in the passivation layer, resulting in a lower mobile oxygen content in the passivation layer within the isolation region 15 and a higher mobile oxygen content in the passivation film layer in other areas. This effectively improves passivation and anti-attenuation effects. In addition, by setting a second recessed structure 177 in the extension portion, it is beneficial for identification and alignment in subsequent processes without affecting the passivation polycrystalline silicon film, thus ensuring the conversion efficiency of the solar cell.

[0171] Please refer to Figures 18-19. The photovoltaic system 1000 in this embodiment may include the battery module 1001 in this embodiment, and the battery module 1001 in this embodiment may include a plurality of back-contact solar cells 100 in this embodiment.

[0172] In embodiments of this disclosure, multiple back-contact solar cells 100 in the battery assembly 1001 can be connected in series to form multiple battery strings. These battery strings can be connected in series, in parallel, or in a series-parallel combination to achieve current collection and output. For example, the connection between individual cells can be achieved by welding solder strips, or the connection between battery strings can be achieved by busbars. In some embodiments, the battery strings can form a cell array, which is then encapsulated together by a front panel, a front encapsulant film, a rear encapsulant film, and a back panel to form the battery assembly 1001.

[0173] In some optional embodiments, a back-contact solar cell includes a first region and a second region disposed on the back surface of a silicon substrate, the first region and the second region being alternately disposed, the first region including a first doped conductive layer, the second region including a second doped conductive layer, the doping types of the first doped conductive layer and the second doped conductive layer being opposite; the direction in which the first region and the second region are alternately arranged is a first direction, both the first region and the second region extending along a third direction, the first direction intersecting the third direction, the back-contact solar cell including a plurality of first doped conductive layers and a plurality of second doped conductive layers; the first doped conductive layers cover at least a portion of the first region, each first region having a first doped conductive layer, at least a portion of the first doped conductive layer having a first recessed structure formed thereon; and the second doped conductive layers cover at least a portion of the second region, each second region having a second doped conductive layer, at least a portion of the second doped conductive layer having a leakage contact portion extending to the first doped conductive layer, and the leakage contact portion extending into the first recessed structure, the leakage contact portion being in leakage contact with the first doped conductive layer at least within the first recessed structure.

[0174] Specifically, referring to Figures 20 and 21, the back-contact solar cell 100 in this embodiment may include a silicon substrate 1, a plurality of first doped conductive layers 161 and a plurality of second doped conductive layers 162.

[0175] The silicon substrate 1 has a light-facing surface 11 and a back-light surface 12. The back-light surface 12 includes a first region 13 and a second region 14 arranged alternately along a first direction. Both the first region 13 and the second region 14 extend along a third direction, which intersects with the first direction.

[0176] Specifically, as shown in Figure 20, the first region 13 and the second region 14 can be alternately arranged along the lateral direction of the silicon substrate 1 and both extend along the longitudinal direction. That is, the first direction can be the lateral direction of the back-contact solar cell 100, and the third direction can be the lateral direction of the back-contact solar cell 100, and the two are perpendicular to each other. Of course, in other embodiments, the first direction and the third direction can also be other directions, for example, they can be the diagonal directions of the silicon substrate 1, and there is no specific limitation here. The first doped conductive layer 161 is disposed on the first region 13 and covers at least a portion of the first region 13. Each first region 13 is provided with the first doped conductive layer 161, and the number of the two is corresponding. At least a portion of the first doped conductive layer 161 has a first recessed structure 173 formed on it.

[0177] The second doped conductive layer 162 is disposed on the second region 14 and covers at least a portion of the second region 14. Each second region 14 is provided with a second doped conductive layer 162, and the number of the two is corresponding. At least a portion of the second doped conductive layer 162 has a leakage contact portion 31 extending to the first doped conductive layer 161, and the leakage contact portion 31 extends into the first recessed structure 173. The leakage contact portion 31 is in leakage contact with the first doped conductive layer 161 at least within the first recessed structure 173.

[0178] It should be noted that in this article, the covering of a certain area or the entire area of ​​a certain surface by a certain layer structure can be a certain layer structure covering another layer structure, the layer structure being directly stacked on the surface or a certain film layer, or other film layers being disposed between the film layer and the surface or film layer. The term "covering" is only used to define the specific setting range of the film layer.

[0179] Furthermore, it should be noted that in this article, "leakage contact" refers to a situation where there is no insulation between the leakage contact portion 31 and the first doped conductive layer 161, but rather leakage conduction forms a leakage point. The two can be in direct contact to form a leakage point, or they can achieve the function of leakage contact by tunneling through other dielectric layers. For example, the leakage contact portion 31 and the first doped conductive layer 161 can be directly provided with a dielectric layer with electrical conduction function (such as a tunneling oxide layer).

[0180] In the back-contact solar cell 100, battery module 1001, and photovoltaic system 1000 of this disclosure embodiment, a first recessed structure 173 is formed on at least a portion of the first doped conductive layer 161. A second doped conductive layer 162 has a leakage contact portion 31 extending onto the first doped conductive layer 161. The leakage contact portion 31 extends partially into the first recessed structure 173 and forms a leakage contact with the first doped conductive layer 161 at least within the first recessed structure 173. Thus, the leakage contact portion 31 of the second doped conductive layer 162 can form a leakage contact with the first doped conductive layer 161 within the first recessed structure 173, thereby forming a leakage point at the first recessed structure 173. This can reduce the reverse breakdown voltage of the back-contact solar cell 100 when it is shaded, thereby improving the hot spot resistance of the back-contact solar cell 100 and reducing the hot spot risk of the battery module 1001. Meanwhile, by setting the first recessed structure 173, the contact area can be increased while ensuring the accuracy of the contact area, further optimizing the hot spot resistance of the back contact solar cell 100 and ensuring the consistency of the hot spot resistance of each back contact solar cell 100 during the production process.

[0181] Specifically, in the embodiments of this disclosure, the silicon substrate 1 can be an N-type silicon substrate 1 or a P-type silicon substrate 1, and there is no specific limitation here. The first doped conductive layer 161 can be an N-type doped layer, and the second doped conductive layer 162 can be a P-type doped layer, or the first doped conductive layer 161 can be a P-type doped layer, and the second doped conductive layer 162 can be a P-type doped layer, and there is no specific limitation here, as long as the polarities of the two are opposite.

[0182] In the embodiments disclosed herein, at least one first recessed structure 173 may be formed on all first doped conductive layers 161, and at least one leakage contact portion 31 may be formed on all second doped conductive layers 162. Alternatively, the first recessed structure 173 may be formed on all first doped conductive layers 161, and some second doped conductive layers 162 may have leakage contacts 31. Or, the first recessed structure 173 may be formed on some first doped conductive layers 161, and some second doped conductive layers 162 may have leakage contacts 31. No specific limitation is made here, as long as the leakage contact area does not cause a significant decrease in the efficiency of the back contact solar cell 100, for example, the efficiency loss is controlled to be within 0.3%.

[0183] Referring to Figure 21, in some embodiments, a first tunneling layer 200 is provided between the first doped conductive layer 161 and the silicon substrate 1 in the first region 13, and a second tunneling layer 400 is provided between the second doped conductive layer 162 and the silicon substrate 1 in the second region 14.

[0184] Thus, by setting the first tunneling layer 200 and the second tunneling layer 400, the passivation effect can be improved. Specifically, both the first tunneling layer 200 and the second tunneling layer 400 can be a tunneling oxide layer, an intrinsic amorphous silicon layer, or other film layers.

[0185] Please continue to refer to Figure 21. In some embodiments, a dielectric layer 60 is provided on the area covered by the leakage contact portion 31 in the first recessed structure 173. The leakage contact portion 31 covers the dielectric layer 60 and makes leakage contact with the first doped conductive layer 161 in the first recessed structure 173 through the dielectric layer 60.

[0186] Thus, by providing the dielectric layer 60, the passivation effect can be improved while the leakage contact 31 can form a leakage contact with the first doped conductive layer 161, thereby improving the passivation effect and the resistance to hot spots. The dielectric layer 60 can be a conductive film layer such as a tunneling oxide layer.

[0187] As shown in Figure 21, in some embodiments, the first doped conductive layer 161 and the second doped conductive layer 162 can both be doped polysilicon layers, and the first tunneling layer 200 and the second tunneling layer 400 can both be tunneling oxide layers.

[0188] As shown in Figure 21, in this case, a passivation layer 18 is also covered on the entire backlight surface 12. The passivation layer 18 is the outermost layer of the backlight surface 12 of the back contact solar cell 100. A first electrode 700 is provided above the first doped conductive layer 161, and a second electrode 800 is provided above the second doped conductive layer 162. The first electrode 700 can penetrate the passivation layer 18 and be conductively connected to the first doped conductive layer 161. The second electrode 800 can penetrate the passivation layer 18 and be conductively connected to the second doped conductive layer 162. The first electrode 700 and the second electrode 800 can be formed by slurry burning-through or trench deposition and electroplating.

[0189] Understandably, in such an embodiment, since the leakage contact portion 31 of the second doped conductive layer 162 extends above the first doped conductive layer 161, the first electrode 700 needs to avoid the leakage contact portion 31. Therefore, in one embodiment, the first electrode 700 can be disposed on one side of the leakage contact portion 31, and the first electrode 700 and the leakage contact portion 31 do not overlap in the thickness direction. The first electrode 700 can be made of a burn-through paste and continuously disposed along a third direction in the portion of the first doped conductive layer 161 not covered by the leakage contact portion 31. Alternatively, it can be formed by creating an electrode trench that extends continuously along a third direction in the passivation layer 18, and then forming the first electrode 700 at the electrode trench by deposition, electroplating, or other methods. Of course, the first electrode 700 may also overlap at least partially with the leakage contact portion 31 in the thickness direction. In this case, intermittent gaps may be formed in the passivation layer 18, that is, electrode grooves may be formed in the area where there is no leakage contact portion 31, and no electrode grooves may be formed at the leakage contact portion 31. Then, the intermittent first electrode 700 may be formed on the first doped conductive layer 161 by deposition and electroplating.

[0190] As shown in Figure 22, in some other embodiments, the first doped conductive layer 161 may be a doped polycrystalline silicon layer, and the second doped conductive layer 162 may be a doped amorphous silicon layer or a doped microcrystalline silicon layer. In such cases, the first tunneling layer 200 may be a tunneling oxide layer or an intrinsic amorphous silicon layer, and the second tunneling layer 400 may be a tunneling oxide layer or an intrinsic amorphous silicon layer.

[0191] As shown in Figure 22, in this embodiment, a conductive film 120, such as a TCO film, is also covered on the entire backlight surface 12. The conductive film 120 can be the outermost layer of the backlight surface 12 of the back-contact solar cell 100. An insulating groove 1201 is formed on the conductive film 120 to separate the portion of the conductive film 120 corresponding to the first region and the portion of the conductive film 120 corresponding to the second region. The first electrode 700 can be respectively disposed on the conductive film 120 in the first region, and the second electrode 800 can be respectively disposed on the conductive film 120 in the second region. In this case, the first electrode 700 and the second electrode 800 can be formed on the conductive film 120 by electroplating. As shown in Figure 21, in this embodiment, the portion of the leakage contact 31 outside the first recessed structure 173 is stacked on the first doped conductive layer 161 in the thickness direction to form a stacked structure. The leakage contact 31 and the first doped conductive layer 161 are conductive in the thickness direction, and the insulating groove 1201 can be formed at the position of the stacked structure.

[0192] In some embodiments, the leakage contact 31 may preferably completely cover all sidewalls and bottom surfaces of the first recessed structure 173. Of course, it may also cover only part of the sidewalls and not the bottom, or only part of the sidewalls and the entire bottom, or only part of the sidewalls and a portion of the bottom, or cover all sidewalls but not the bottom. No specific limitation is made here.

[0193] Referring to Figure 21, in some embodiments, the first recessed structure 173 completely penetrates the first doped conductive layer 161 in the thickness direction (i.e., the thickness direction of the back contact solar cell 100) to expose the silicon substrate 1 at the first recessed structure 173. A leakage contact portion 31 covers the silicon substrate 1 exposed from the first recessed structure 173 and at least a portion of the sidewall surface of the first recessed structure 173.

[0194] Thus, the first recessed structure 173 completely penetrates the first doped conductive layer 161. The first recessed structure 173 is a through-slot penetrating the first doped conductive layer 161. The silicon substrate 1 is exposed at the first recessed structure 173. The leakage contact 31 forms a leakage contact with the first doped conductive layer 161 on the side wall of the first recessed structure 173 to improve the hot spot resistance performance. At the same time, the leakage contact 31 contacts the silicon substrate 1 at the bottom of the first recessed structure 173. When the second doped conductive layer 162 is the emitter doped layer of the back contact solar cell 100, this arrangement can further increase the emitter area of ​​the back contact solar cell 100, thereby improving the efficiency of the back contact solar cell 100.

[0195] Specifically, in such an embodiment, the leakage contact 31 forms a leakage contact with the first doped conductive layer 161 only on the sidewall surface of the first recessed structure 173, while the portion of the leakage contact 31 located at the bottom of the first recessed structure 173 acts as an emitter.

[0196] Please refer to Figure 21. In some embodiments, the first recessed structure 173 completely penetrates the first doped conductive layer 161 and forms a trench 125 on the silicon substrate 1. The recessed depth of the trench 125 on the silicon substrate 1 is 1μm-6μm.

[0197] Thus, by setting the first recessed structure 173 to completely penetrate the first doped conductive layer 161 and form a trench 125 on the silicon substrate 1, the leakage contact portion 31 will not form a leakage contact with the first doped conductive layer 161 at the bottom of the first recessed structure 173, but will directly contact the silicon substrate 1. When the second doped conductive layer 162 is the emitter, the area of ​​the emitter can be increased, thereby improving efficiency.

[0198] Specifically, the indentation depth of the trench 125 on the silicon substrate 1 can be, for example, any value of 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm or 1μm-6μm.

[0199] Furthermore, in some embodiments, an inner expansion layer (not shown) is formed in a portion of the silicon substrate 1 corresponding to the first region 13, and the polarity of the inner expansion layer is the same as that of the first doped conductive layer 161; the first recessed structure 173 does not penetrate the inner expansion layer, and the leakage contact portion 31 makes leakage contact with the inner expansion layer away from the surface of the silicon substrate 1.

[0200] Thus, in addition to forming a leakage contact with the first doped conductive layer 161 at the side wall of the first recessed structure 173, the leakage contact portion 31 also forms a leakage contact with the inner expansion layer on the bottom surface of the first recessed structure 173, which can increase the leakage contact area and further improve the anti-hot spot performance.

[0201] Of course, in some embodiments, the first recessed structure 173 may also penetrate the inner expansion layer, and the leakage contact portion 31 makes leakage contact with the side of the inner expansion layer exposed at the first recessed structure 173. In this way, in addition to making leakage contact with the first doped conductive layer 161, the leakage contact portion 31 also makes leakage contact with the side of the inner expansion layer, thereby improving the hot spot resistance performance.

[0202] Referring to Figure 23, in some embodiments, the first recessed structure 173 does not completely penetrate the first doped conductive layer 161 in the thickness direction, and the leakage contact portion 31 covers at least a portion of the bottom surface of the first recessed structure 173 and at least a portion of the sidewall surface of the first recessed structure 173.

[0203] Thus, the first recessed structure 173 is a blind trench that does not completely penetrate the first doped conductive layer 161, and the leakage contact portion 31 can form leakage contact with the first doped conductive layer 161 on both the bottom surface and the side wall surface of the first recessed structure 173.

[0204] Furthermore, in some embodiments, the first recessed structure 173 does not completely penetrate the first doped conductive layer 161 in the thickness direction, and the recess depth of the first recessed structure 173 is 20nm-200nm.

[0205] In this way, by reasonably controlling the recessed depth of the first recessed structure 173, the leakage contact area formed by the leakage contact part 31 in the first recessed structure 173 can be controlled within a reasonable range, avoiding excessive efficiency loss.

[0206] Specifically, in such an embodiment, the recessed depth of the first recessed structure 173 may be, for example, any value between 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm or 20nm-20nm, and is not limited herein.

[0207] Please refer to Figures 21 and 24. In some embodiments, the first doped conductive layer 161 has opposing first side 201 and second side 202 in a first direction, and the first recessed structure 173 does not penetrate the first side 201 and second side 202 (as shown in Figure 24). In the first direction, the first doped conductive layer 161 is present on both sides of the first recessed structure 173.

[0208] In this way, the area of ​​the first recessed structure 173 can be controlled within a reasonable range, thus avoiding excessive efficiency loss.

[0209] Specifically, as shown in FIG24, in such an embodiment, the first doped conductive layer 161 has opposing third side surfaces 203 and fourth side surfaces 204 in a third-direction orientation. The first recessed structure 173 may be located in the middle region of the first doped conductive layer 161. The first recessed structure 173 only has a notch facing away from the silicon substrate 1, that is, the first recessed structure 173 does not penetrate through the third side surface 203 and the fourth side surface 204. Of course, in some embodiments, the first recessed structure 173 may also penetrate through at least one of the third side surface 203 and the fourth side surface 204 in a third-direction orientation.

[0210] Furthermore, in some embodiments, the number of first recessed structures 173 on a single first doped conductive layer 161 can be single or multiple. In the case of a single recessed structure 173, it may not penetrate the first side 201 and the second side 202, nor the third side 203 and the fourth side 204. Alternatively, it may penetrate the third side 203 but not the fourth side 204, or it may penetrate both the third side 203 and the fourth side 204 simultaneously (that is, the first recessed structure 173 extends continuously in the third direction through both ends of the first doped conductive layer 161 in the third direction).

[0211] In several cases, in some embodiments, all first recessed structures 173 may not penetrate the third side 203 and the fourth side 204. In other embodiments, the first recessed structure 173 closest to the third side 203 may penetrate the third side 203, and the first recessed structure 173 closest to the fourth side 204 may also penetrate the fourth side 204; specific details are not limited here.

[0212] Of course, referring to Figures 25 and 26, in some embodiments, the first recessed structure 173 may also penetrate at least one of the first side surface 201 and the second side surface 202. For example, as shown in Figures 25 and 26, in one example, the first recessed structure 173 may penetrate the first side surface 201 and the second side surface 202 of the first doped conductive layer 161 in a first direction. In another example, the first recessed structure 173 may also penetrate only the first side surface 201 or only the second side surface 202 in the first direction; no specific limitation is made here.

[0213] Specifically, as shown in FIG25, in some embodiments, a first recessed structure 173 penetrating the first side 201 and the second side 202 can be formed on all the first doped conductive layers 161. Two adjacent second doped conductive layers 162 are connected by a leakage contact portion 31 located in the first recessed structure 173. That is, the leakage contact portion 31 traverses the first doped conductive layer 161 in the first recessed structure 173 along the first direction to connect two adjacent second doped conductive layers 162 together.

[0214] In such an embodiment, the first recessed structure 173 may penetrate the first doped conductive layer 161 in the thickness direction. In this case, the leakage contact portion 31 makes leakage contact with the first doped conductive layer 161 at the sidewall surface of the first recessed structure 173. Of course, the first recessed structure 173 may not penetrate the first doped conductive layer 161 in the thickness direction. In this case, the leakage contact portion 31 makes leakage contact with the first doped conductive layer 161 at the sidewall surface and / or bottom surface of the first recessed structure 173.

[0215] As shown in Figure 25, when the first recessed structure 173 simultaneously penetrates the first side surface 201 and the second side surface 202, the leakage contact portion 31 can completely cover the bottom surface of the first recessed structure 173. In this case, the first electrode 700 can adopt the intermittent electrode structure formed by opening intermittent electrode grooves and by deposition and electroplating as described above.

[0216] Referring to Figures 21 and 23, in some embodiments, the leakage contact 31 includes a first portion 311 located within the first recessed structure 173 and a second portion 312 stacked on the surface of the first doped conductive layer 161 facing away from the silicon substrate 1; the first portion 311 makes leakage contact with the first doped conductive layer 161, and an insulating dielectric layer 110 is provided between the second portion 312 and the first doped conductive layer 161.

[0217] In this way, only the first part 311 of the leakage contact portion 31 located in the first recessed structure 173 forms a leakage contact with the first doped conductive layer 161, which can control the leakage contact area of ​​the back contact solar cell 100 and avoid excessive efficiency loss due to an excessively large leakage contact area.

[0218] Specifically, in such an embodiment, the second portion 312 covers the area outside the first recessed structure 173. The second portion 312 is insulated from the first doped conductive layer 161 by the insulating dielectric layer 110. The leakage contact portion 31 forms a leakage contact with the first doped conductive layer 161 only through the first portion 311. The insulating dielectric layer 110 can be a dielectric film layer with insulating function, such as a silicon oxide film layer or a silicon nitride film layer.

[0219] Of course, it is understandable that in some embodiments, the second part 312 may also make leakage contact with the surface of the first doped conductive layer 161 away from the silicon substrate 1, provided that the efficiency of the back contact solar cell 100 is not significantly reduced. No specific restrictions are imposed here.

[0220] Please continue to refer to Figures 21 and 23. In some embodiments, the leakage contact 31 extends along the side of the first doped conductive layer 161 to the surface of the first doped conductive layer 161 away from the silicon substrate 1 and into the first recessed structure 173. The leakage contact 31 also forms a leakage contact with the first doped conductive layer 161 at the side of the first doped conductive layer 161.

[0221] Thus, the leakage contact portion 31 also forms a leakage contact with the first doped conductive layer 161 at the side of the first doped conductive layer 161, which can increase the area of ​​the leakage contact and further improve the anti-hot spot performance.

[0222] Specifically, as shown in Figures 21 and 23, in such an embodiment, the leakage contact portion 31 of the second doped conductive layer 162 located on one side of the first side 201 can extend along the first side 201 of the first doped conductive layer 161 to the surface of the first doped conductive layer 161 away from the silicon substrate 1, and then further extend into the first recessed structure 173, whereby the leakage contact portion 31 forms a leakage contact with the first side 201.

[0223] Of course, in some embodiments, the leakage contact portion 31 of the second doped conductive layer 162 located on one side of the second side 202 can extend along the second side 202 of the first doped conductive layer 161 to the surface of the first doped conductive layer 161 away from the silicon substrate 1, and then further extend into the first recessed structure 173, and the leakage contact portion 31 and the second side 202 also form a leakage contact, which is not limited here.

[0224] Referring to Figure 24, in some embodiments, in the first direction, the first recessed structure 173 has a first predetermined distance H1 between it and the side of the first doped conductive layer 161 (i.e., the side closest to the first recessed structure 173, either the first side 201 or the second side 202). The size of the first predetermined distance H1 can be 10μm-200μm.

[0225] In this way, the distance between the first recessed structure 173 and the first side 201 or the second side 202 of the first doped conductive layer 161 is not too large, which would cause the distance between the first electrode 700 and the first side 201 or the second side 202 to be too large, thus preventing the first electrode 700 from being centered. This improves the collection efficiency of the first electrode 700. It also avoids the distance between the recess and the first side 201 or the second side 202 of the first doped conductive layer 161 being too small, which would greatly increase the difficulty of the process.

[0226] Specifically, as shown in Figure 24, in such an embodiment, the first recessed structure 173 may not penetrate the first side 201 and the second side 202. The first recessed structure 173 may be disposed close to the first side 201. In this case, the second doped conductive layer 162 close to the first side 201 has a leakage contact portion 31, which extends into the first recessed structure 173. The first electrode 700 may be disposed between the first recessed structure 173 and the second side 202, and it may be a continuous structure. By setting the first predetermined distance H1 within the above-mentioned reasonable range, it is possible to avoid the collection efficiency of the first electrode 700 being greatly reduced due to the excessive distance between the first electrode 700 and the first side 201.

[0227] In such an embodiment, the size of the first predetermined distance H1 can be, for example, any value between 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, or 10μm-200μm.

[0228] Please refer to Figure 24. In some embodiments, the length L1 of the first recessed structure 173 in the first direction is 10 μm-80 μm.

[0229] Thus, by reasonably controlling the length of the first recessed structure 173 in the first direction, it is also possible to avoid the first electrode 700 being unable to be centered due to the excessive width of the first recessed structure 173, which would result in a significant reduction in collection efficiency. In other words, by setting the length of the first recessed structure 173 in the first direction within this reasonable range, the collection efficiency of the first electrode 700 can be improved.

[0230] Specifically, in such an embodiment, the length L1 of the first recessed structure 173 in the first direction can be, for example, any value between 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm or 10μm-80μm.

[0231] Please refer to Figure 24. In some embodiments, the length L2 of the first recessed structure 173 is 10 μm-500 μm in the third direction.

[0232] Thus, by setting the length of the first recessed structure 173 in the third direction within this reasonable range, it is possible to avoid excessive efficiency loss due to excessively large leakage contact area in a single first recessed structure 173.

[0233] Specifically, in such an embodiment, the length L2 of the first recessed structure 173 in the third direction can be, for example, any value between 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, 300 μm, 320 μm, 340 μm, 360 μm, 380 μm, 400 μm, 420 μm, 440 μm, 460 μm, 480 μm, 500 μm, or between 10 μm and 500 μm.

[0234] In some embodiments, the ratio between the length L2 of the first recessed structure 173 in the third direction and the length L1 of the first recessed structure 173 in the first direction is greater than or equal to 2.

[0235] Thus, in order to improve collection efficiency, when the slot width of the first recessed structure 173 is small, by setting the length of the first recessed structure 173 in the third direction to be larger, the leakage contact area can be increased, thereby ensuring the anti-hot spot performance.

[0236] Please refer to Figures 20, 24 and 25. In some embodiments, there are multiple first recessed structures 173 on a single first doped conductive layer 161, and the multiple first recessed structures 173 are arranged at intervals in the third direction.

[0237] Thus, by providing multiple isolated first recessed structures 173 on the first doped conductive layer 161, it is possible to avoid excessive efficiency loss due to excessively large leakage contact area on a single first doped conductive layer 161.

[0238] Referring to Figure 24, in some embodiments, the first recessed structure 173 on the first doped conductive layer 161 can be arranged in a row in the third direction, which can simplify the process and improve efficiency.

[0239] Of course, in some embodiments, in order to avoid the first recessed structure 173 being too concentrated, the first recessed structure 173 on the first doped conductive layer 161 can be arranged in at least two columns in the third direction.

[0240] Furthermore, in some embodiments, in the third direction, the distance H2 between two adjacent first recessed structures 173 is 1cm-10cm.

[0241] In this way, the spacing H2 between two adjacent first recessed structures 173 can be avoided from being too small, resulting in excessive concentration of leakage points and the inability to dissipate heat in time, which would lead to a significant increase in temperature.

[0242] Specifically, in such an embodiment, the distance H2 between two adjacent first recessed structures 173 can be, for example, any value between 1cm, 1.5cm, 2cm, 2.5cm, 3cm, 3.5cm, 4cm, 4.5cm, 5cm, 5.5cm, 6cm, 6.5cm, 7cm, 7.5cm, 8cm, 8.5cm, 9cm, 9.5cm, 10cm or 1cm-10cm.

[0243] Furthermore, in such an embodiment, in the third direction, the distance H2 between two adjacent first recessed structures 173 is preferably greater than or equal to 2 cm and less than 4 cm.

[0244] Thus, through the research and demonstration of the inventors of this disclosure, setting the spacing within this preferred range can minimize the heat concentration when the number of the first recessed structures 173 is set to a large extent. In other words, this can balance the relationship between the anti-hot spot performance and the excessive heat concentration, so as to achieve the optimal matching effect.

[0245] Specifically, in such an embodiment, the distance H2 between two adjacent first recessed structures 173 can preferably be, for example, 2cm, 2.2cm, 2.4cm, 2.6cm, 2.8cm, 3cm, 3.1cm, 3.2cm, 3.3cm, 3.4cm, 3.5cm, 3.6cm, 3.7cm, 3.9cm, or 3.95cm.

[0246] In some embodiments, the regions in the first doped conductive layer 161 and the second doped conductive layer 162 not covered by the leakage contact portion 31 are non-leakage regions, and the regions in the first doped conductive layer 161 and the second doped conductive layer 162 other than the non-leakage regions are leakage regions. To reduce recombination in the non-leakage regions, the number of first recessed structures 173 in the non-leakage regions is greater than the number of first recessed structures 173 in the leakage regions per unit length.

[0247] In some embodiments, in the back-contact solar cell 100, the distribution density of the first recessed structure 173 is 0.01 structures / cm². 2 -1.5 pieces / cm 2 Thus, by reasonably controlling the distribution density of the first recessed structure 173, the leakage points can be avoided from being too concentrated.

[0248] In this embodiment, the distribution density of the first recessed structure 173 refers to the ratio between the sum of the number of first recessed structures 173 on the back contact solar cell 100 and the area of ​​the back surface 12 of the back contact solar cell 100. Specifically, the distribution density of the first recessed structure 173 can be, for example, 0.01 structures / cm².2 0.05 pieces / cm 2 0.1 pieces / cm 2 0.2 pieces / cm 2 0.3 pieces / cm 2 0.4 pieces / cm 2 0.5 pieces / cm 2 0.6 pieces / cm 2 0.7 pieces / cm 2 0.8 pieces / cm 2 0.9 pieces / cm 2 1 piece / cm 2 1.1 pieces / cm 2 1.2 pieces / cm 2 1.3 pieces / cm 2 1.4 pieces / cm 2 1.5 pieces / cm 2 Or 0.01 per cm 2 -1.5 pieces / cm 2 Any value between.

[0249] In some embodiments, in a single first recessed structure 173, the area of ​​the leakage contact 31 in contact with the first doped conductive layer 161 is 1.2 μm. 2 -1500μm 2 .

[0250] Thus, by controlling the leakage contact area in a single first recessed structure 173 within this reasonable range, it is possible to improve the anti-hot spot performance while ensuring that the efficiency loss is not too large.

[0251] Specifically, in such an embodiment, the area of ​​the leakage contact 31 in contact with the first doped conductive layer 161 can be, for example, 1.2 μm. 2 2μm 2 5μm 2 10μm 2 50μm 2 100μm 2 200μm 2 300μm 2 350μm 2 400μm 2 450μm 2 480μm 2 _500μm 2 600μm 2 700μm 2 800μm 2 900μm 2 1000μm2 1100μm 2 1200μm 2 1300μm 2 1400μm 2 1500μm 2 Or 1.2μm 2 -1500μm 2 Any value between.

[0252] In some embodiments, in the back-contact solar cell 100, the ratio of the sum of the areas of all leakage contacts 31 and the leakage contacts of the first doped conductive layer 161 to the back-light area of ​​the back-contact solar cell 100 (i.e., the area of ​​the back-light surface 12 of the silicon substrate 10) is 4.5*10-8-1.5*10-5.

[0253] Thus, by setting the ratio of the leakage contact area to the backlight surface 12 within this reasonable range, the proportion of the leakage contact area can be set too large, which would seriously affect the efficiency of the back contact solar cell 100. In other words, the efficiency of the back contact solar cell 100 can be guaranteed while ensuring the anti-hot spot performance.

[0254] Specifically, in such an embodiment, the ratio of the areas of the two can be, for example, 4.5*10-8, 5*10-8, 6*10-8, 7*10-8, 8*10-8, 9*10-8, 1*10-7, 1*10-6, 1*10-5, 1.5*10-5, or any other value between 4.5*10-8 and 1.5*10-5, without any specific limitation here.

[0255] Please refer to Figures 27 and 29. In some embodiments, the second region 14 is a groove 123 formed on the silicon substrate 1. The first doped conductive layer 161 has a first protrusion 22 extending above the groove 123. The leakage contact portion 31 extends along the sidewall of the groove 123, wraps around the first protrusion 22, extends and covers the first doped conductive layer 161, and further extends into the first recessed structure 173.

[0256] In this way, the leakage contact portion 31 and the first protrusion 22 can also form a leakage contact, thereby improving the anti-hot spot performance.

[0257] Specifically, in such an embodiment, the first doped conductive layer 161 may be a P-type doped layer, and the second doped conductive layer 162 may be an N-type doped layer. The P-type doped layer has a first protrusion 22. The leakage contact portion 31 may form a leakage contact only with the surface of the first protrusion 22 facing the groove 123, or it may form a leakage contact simultaneously with the surface of the first protrusion 22 facing the groove 123 and the sidewall surface of the first protrusion 22. No specific limitation is made here.

[0258] Referring to FIG28, in some embodiments, the second region 14 is a groove 123 formed on the silicon substrate 1, and the first doped conductive layer 161 does not completely cover the first region 13, so that the first region 13 has an exposed area 124 not covered by the first doped conductive layer 161 between the first doped conductive layer 161 and the groove 123, and the leakage contact portion 31 extends to the exposed area 124 and covers the exposed area 124.

[0259] Thus, when the second doped conductive layer 162 is the emitter of the back contact solar cell 100, the area of ​​the emitter can be increased by setting the bare area 124, thereby improving the efficiency of the back contact solar cell 100. At the same time, due to the setting of the bare area 124, the first doped conductive layer 161 will not be exposed at the cross-section of the groove 123, which can reduce recombination.

[0260] Specifically, in such an embodiment, the first doped conductive layer 161 is an N-type doped layer, and the second doped conductive layer 162 is a P-type doped layer.

[0261] Furthermore, in such an embodiment, the length L4 of the exposed area 124 in the first direction is 0.3 μm-50 μm.

[0262] Thus, by setting the length of the exposed area 124 in the first direction within this reasonable range, it is possible to avoid the situation where the width is too small, resulting in a large recombination, and it is also possible to avoid the situation where the length is too large, resulting in an area without the first doped conductive layer 161 being too large, which would lead to a low carrier collection efficiency and affect the overall efficiency of the battery.

[0263] Specifically, in such an embodiment, the length L4 of the exposed area 124 can be, for example, any value between 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 15μm, 20μm, 25μm, 30μm, 40μm, 45μm, 50μm, or 0.3μm-50μm, and is not specifically limited herein.

[0264] In some embodiments, the length L4 of the exposed area 124 in the first direction is preferably 1 μm-20 μm.

[0265] Referring to Figure 29, in some embodiments, the first recessed structure 173 completely penetrates the first doped conductive layer 161 and forms a trench 125 on the silicon substrate 1. The first doped conductive layer 161 on both sides of the trench 125 has a second protrusion 23 extending above the trench 125. The leakage contact portion 31 surrounds at least one second protrusion 23 and extends into the first recessed structure 173.

[0266] In this way, leakage contact 31 and second protrusion 23 can also form leakage contact, thereby improving the anti-hot spot performance.

[0267] Specifically, in such an embodiment, the first doped conductive layer 161 may be a P-type doped layer, the second doped conductive layer 162 may be an N-type doped layer, the P-type doped layer has a second protrusion 23, and the leakage contact portion 31 may only form a leakage contact with the surface of the second protrusion 23 facing the groove 123, or it may simultaneously form a leakage contact with the surface of the second protrusion 23 facing the groove 123 and the sidewall surface of the second protrusion 23. The specific details are not limited here.

[0268] Please refer to 30. In some embodiments, the first recessed structure 173 completely penetrates the first doped conductive layer 161 and forms a trench 125 on the silicon substrate 1. The first doped conductive layer 161 located on both sides of the trench 125 has a second preset distance L5 from the edge of the trench 125.

[0269] Thus, by setting the second preset distance L5, the first doped conductive layer 161 will not be exposed at the cross-section of the trench 125, which can reduce recombination.

[0270] Specifically, in such an embodiment, the first doped conductive layer 161 is an N-type doped layer, and the second doped conductive layer 162 is a P-type doped layer.

[0271] Furthermore, in such an embodiment, the second preset distance L5 can be 0.3μm-50μm.

[0272] Thus, by setting the size of the second preset distance L5 within this reasonable range, it is possible to avoid the second preset distance L5 being too small, which would result in a large recombination, and it is also possible to avoid the length being too large, which would result in an area without the first doped conductive layer 161 being too large, which would result in a low carrier collection efficiency and affect the overall efficiency of the battery.

[0273] Specifically, in such embodiments, the size of the second preset distance L5 can be, for example, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 15μm, 20μm,

[0274] Any value between 25μm, 30μm, 40μm, 45μm, 50μm or 0.3μm-50μm, without any specific limitation.

[0275] Referring to Figure 31, in some embodiments, the second region 14 is a groove 123 formed on the silicon substrate 1. At the edge of the first doped conductive layer 161 facing the groove 123, the first doped conductive layer 161 has a stepped structure 24. The leakage contact portion 31 covers the side of the first doped conductive layer 161 and the stepped structure 24, and the leakage contact portion 31 makes leakage contact with the first doped conductive layer 161 at the stepped structure 24.

[0276] Thus, by setting the stepped structure 24, the leakage contact 31 can form a leakage contact with the first doped conductive layer 161 at the stepped structure 24, which can improve the electrode of the leakage contact and thereby improve the resistance to hot spot formation of the back contact solar cell 100.

[0277] Specifically, as shown in FIG31, at the edge of the first doped conductive layer 161 facing the groove 123, the first doped conductive layer 161 has a stepped surface, and the leakage contact portion 31 is in leakage contact with the first doped conductive layer 161 through the connection surface covering the stepped surface and the connection surface connecting the stepped surface and the outermost surface of the first doped conductive layer 161 away from the silicon substrate 1.

[0278] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A back contact solar cell, comprising a first region, a second region and an isolation region on a back surface of a silicon substrate, the first region and the second region are arranged alternately, the isolation region is located between the first region and the second region, the first region comprises a first doped conductive layer, the second region comprises a second doped conductive layer, the first doped conductive layer and the second doped conductive layer are opposite in doping type;one side of the first region close to the isolation region is provided with a recess structure, wherein, When the silicon substrate is an N-type silicon substrate, the first region is a P-type doped region, and the second region is an N-type doped region, the P-type doped region is provided with n1 recessed structures on a side close to the isolation region, and the N-type doped region is provided with n2 recessed structures on a side close to the isolation region, wherein n1>n2.

2. The back contact solar cell of claim 1, wherein, The first region is provided with discontinuous recessed structures on a side close to the isolation region; and / or the second region is provided with recessed structures on a side close to the isolation region.

3. The back contact solar cell of claim 2, wherein, The second region is provided with discontinuous recessed structures on a side close to the isolation region.

4. The back contact solar cell according to any one of claims 1 to 3, wherein, The recessed structure comprises a first unit region and a first recessed structure, the first unit region is arranged around the first recessed structure, the first recessed structure comprises a pit and a protrusion arranged in the pit; or the first region comprises an extension part extending above the isolation region, the recessed structure comprises a second unit region and a second recessed structure, the second unit region is arranged around the second recessed structure, the extension part is provided with the second recessed structure, and the second recessed structure is a blind hole or a through hole.

5. The back contact solar cell according to claim 4, wherein, The height of the protrusion is less than or equal to the depth of the pit; or The shape of the protrusion comprises a pyramid type and / or a prism type; or the silicon substrate has a light-receiving surface arranged opposite to the back surface, and along a direction of the light-receiving surface towards the back surface, the protrusion comprises the silicon substrate and a passivation layer, and the sidewall of the pit comprises the passivation layer.

6. The back contact solar cell according to claim 4, wherein, The width of the bottom of the protrusion is 0.1 μm-1.5 μm, and the height of the protrusion is 0.01 μm-10 μm; or The width of the pit opening is 0.1 μm-2 μm, and the depth of the pit is 0.01 μm-10 μm.

7. The back contact solar cell of claim 4, wherein, The passivation layer of the back contact solar cell wraps the extension part, and the second recessed structure penetrates the extension part and the passivation layer; or the width of the second recessed structure is 0.1 μm-1.5 μm.

8. The back contact solar cell of claim 2, wherein, The plurality of recessed structures form an isolation transition region, and the width of the isolation transition region is 5 μm-30 μm.

9. The back contact solar cell of claim 8, wherein, The width of the isolation transition region is 10 μm-15 μm.

10. The back contact solar cell of claim 4, wherein, The tunneling layer of the back contact solar cell comprises a first tunneling layer arranged between the first conductive doped layer and the silicon substrate between the first region, the edges of the first doped conductive layer, the first tunneling layer and the silicon substrate of the first region all extend to the center of the opening of the isolation region to form the extension part, or only the first doped conductive layer extends to the center of the opening of the isolation region to form the extension part; And / or, the tunneling layer of the back contact solar cell further comprises a second tunneling layer, the second tunneling layer is arranged between the second doped conductive layer and the silicon substrate of the second region; or the passivation layer of the back contact solar cell covers the first doped conductive layer, the second doped conductive layer and the isolation region, the back contact solar cell further comprises a first electrode and a second electrode, the first electrode is connected with the first doped conductive layer through the passivation layer, and the second electrode is connected with the second doped conductive layer through the passivation layer.

11. The back contact solar cell of claim 10, wherein, The diameter of the second recess structure is 1.5 μm-5 μm; or the length of the extension part is 0.1 μm-40 μm.

12. The back contact solar cell of claim 1, wherein, The side of the first region close to the isolation region comprises a first target region, the length of the first target region along the extension direction of the isolation region is greater than 50 μm, and the first target region does not comprise the recess structure; the side of the second region close to the isolation region comprises a second target region, the length of the second target region along the extension direction of the isolation region is greater than 50 μm, and the second target region does not comprise the recess structure.

13. A back contact solar cell comprising: A silicon substrate, the silicon substrate has opposite light-receiving surfaces and back surfaces, the back surfaces comprise first regions and second regions arranged alternately along a first direction, the first regions and the second regions both extend along a third direction, and the third direction intersects the first direction; A plurality of first doped conductive layers, the first doped conductive layers are arranged on the first regions and cover at least part of the first regions, the first doped conductive layers are arranged on each of the first regions, and at least part of the first doped conductive layers are formed with first recess structures; And A plurality of second doped conductive layers, the second doped conductive layers are arranged on the second regions and cover at least part of the second regions, the second doped conductive layers are arranged on each of the second regions, at least part of the second doped conductive layers have leakage contact parts extending to the first doped conductive layers, and the leakage contact parts partially extend into the first recess structures, and the leakage contact parts are in leakage contact with the first doped conductive layers at least in the first recess structures.

14. The back contact solar cell of claim 13, wherein, The leakage contact part comprises a first part in the first recess structure and a second part laminated on the surface of the first doped conductive layer away from the silicon substrate, the first part is in leakage contact with the first doped conductive layer, and the second part and the first doped conductive layer have an insulating medium layer therebetween, or the second part is in leakage contact with the surface of the first doped conductive layer away from the silicon substrate; Or In the first direction, the leakage contact part extends to the surface of the first doped conductive layer away from the silicon substrate and into the first recess structure along the side surface of the first doped conductive layer, and the leakage contact part also forms leakage contact with the first doped conductive layer at the side surface of the first doped conductive layer; Or In the first direction, the first recessed structure has a first predetermined distance with the side surface of the first doped conductive layer, the first predetermined distance is 10 μm-200 μm in size; Or In the first direction, the length of the first recessed structure is 10 μm-80 μm, and / or in the third direction, the length of the first recessed structure is less than 10 μm-500 μm.

15. The back contact solar cell of claim 14, wherein, The ratio between the length of the first recessed structure in the third direction and the length of the first recessed structure in the first direction is greater than or equal to 2.

16. The back contact solar cell of claim 13, wherein, The first doped conductive layer has opposite first and second side surfaces in the first direction, the first recessed structure does not penetrate the first and second side surfaces, and the first doped conductive layer is present on both sides of the first recessed structure in the first direction; Or The first doped conductive layer has opposite first and second side surfaces in the first direction, the first recessed structure penetrates at least one of the first and second side surfaces; or The first recessed structure completely penetrates the first doped conductive layer in the thickness direction of the first doped conductive layer, so that the silicon substrate is exposed at the first recessed structure, the leakage contact covers the silicon substrate exposed from the first recessed structure, and covers at least part of the side wall surface of the first recessed structure; or The first recessed structure does not completely penetrate the first doped conductive layer in the thickness direction of the first doped conductive layer, and the leakage contact covers at least part of the bottom surface of the first recessed structure and at least part of the side wall surface of the first recessed structure; or The first recessed structure completely penetrates the first doped conductive layer in the thickness direction of the first doped conductive layer and forms a groove on the silicon substrate, the recessed depth of the groove in the thickness direction of the silicon substrate is 1 μm-6 μm; or The first recessed structure completely penetrates the first doped conductive layer in the thickness direction of the first doped conductive layer and forms a groove on the silicon substrate, the first doped conductive layer on both sides of the groove has a second protruding portion extending above the groove, and the leakage contact surrounds at least one second protruding portion and extends into the first recessed structure; or The first recessed structure completely penetrates the first doped conductive layer in the thickness direction of the first doped conductive layer and forms a groove on the silicon substrate, and in the first direction, the first doped conductive layer on both sides of the groove has a second predetermined distance with the edge of the groove.

17. The back contact solar cell of claim 16, wherein, The portion of the silicon substrate corresponding to the first region has an inner expansion layer formed therein, the polarity of the inner expansion layer is the same as the doping type of the first doped conductive layer; Wherein, the first recessed structure does not penetrate the inner expansion layer, and the leakage contact contacts the inner expansion layer away from the surface of the silicon substrate; or The first recessed structure penetrates the inner extension layer, and the electrically conductive contact is in electrically conductive contact with the inner extension layer at the side of the first recessed structure.

18. The back contact solar cell of claim 13, wherein, The second region is a groove formed on the silicon substrate, the first doped conductive layer has a first protruding portion extending above the groove, and the electrically conductive contact extends around the first protruding portion along the sidewall of the groove, extends to the first doped conductive layer, and extends into the first recessed structure; or The second region is a groove formed on the silicon substrate, the first doped conductive layer does not completely cover the first region, so that the first region has an exposed area between the first doped conductive layer and the groove, and the electrically conductive contact extends to and covers the exposed area. Or At the edge of the first doped conductive layer on the side facing the groove, the first doped conductive layer forms a step structure, and the electrically conductive contact covers the step structure and is in electrically conductive contact with the first doped conductive layer at the step structure.

19. The back contact solar cell of claim 13, wherein, A dielectric layer is provided on the area in the first recessed structure covered by the electrically conductive contact, the electrically conductive contact covers the dielectric layer, and the electrically conductive contact is in electrically conductive contact with the first doped conductive layer through the dielectric layer in the first recessed structure.

20. The back contact solar cell of claim 16, wherein, The second preset distance is 0.3 μm to 50 μm.

21. The back contact solar cell of claim 13, wherein, The first recessed structure does not completely penetrate the first doped conductive layer in the thickness direction of the first doped conductive layer, and the depth of the first recessed structure is 20 nm to 200 nm; or on a single first doped conductive layer, the number of first recessed structures is multiple, and the multiple first recessed structures are arranged at intervals in the third direction.

22. The back contact solar cell of claim 13, wherein, In the third direction, the distance between two adjacent first recessed structures is 1 cm to 10 cm; or the multiple first recessed structures are arranged into at least two rows in the third direction.

23. The back contact solar cell of claim 13, wherein, In the back contact solar cell, the distribution density of the first recessed structure is 0.01 / cm 2 -1.5 / cm 2 ; or in a single first recessed structure, the size of the area where the leakage contact part is in leakage contact with the first doped conductive layer is 1.2 μm 2 -1500 μm 2 ; or in the back contact solar cell, the ratio of the sum of the areas where all the leakage contact parts are in leakage contact with the first doped conductive layer to the back surface area of the back contact solar cell is 4.5*10 -8 -1.5*10 -5 .

24. The back contact solar cell of claim 13, wherein, The area of the first doped conductive layer and the second doped conductive layer that is not covered by the electrically conductive contact is a non-electrically conductive area, and the area of the first doped conductive layer and the second doped conductive layer other than the non-electrically conductive area is an electrically conductive area. In the same unit length, the number of first recessed structures in the non-electrically conductive area is greater than the number of first recessed structures in the electrically conductive area.

25. A photovoltaic module comprising the back contact solar cell of any one of claims 1 to 24.

26. A photovoltaic system comprising the photovoltaic module of claim 25.

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