BACK-CONTACT SOLAR CELL, PHOTOVOLTAIC MODULE AND PHOTOVOLTAIC SYSTEM

Abstract

The present disclosure provides a back-contacted solar cell consisting of p-doped zones, n-doped zones and isolation zones, wherein the p-doped zones and the n-doped zones are arranged alternately on an unilluminated side of an n-doped silicon substrate and the isolation zone is located between the p-doped zone and the n-doped zone, wherein the side of the p-doped zone facing the isolation zone is provided with n1 recessed structures and the side of the n-doped zone facing the isolation zone is provided with n2 recessed structures, wherein n1 > n2.

Description

Cross-reference to the related applications

[0001] The present disclosure claims priority from Chinese patent application 202411017194.6, filed on July 26, 2024, with the Chinese National Intellectual Property Administration, entitled "Backside Contacted Solar Cell, Photovoltaic Module and Photovoltaic System", priority from Chinese patent application 202411151681.1, filed on August 20, 2024, with the Chinese National Intellectual Property Administration, entitled "Backside Contacted Cell, Photovoltaic Module and Photovoltaic System", and priority from Chinese patent application 202411231591.3, filed on September 3, 2024, with the Chinese National Intellectual Property Administration, entitled "Backside Contacted Cell, Photovoltaic Module and Photovoltaic System", the entire contents of which are hereby incorporated by reference. Technical field

[0002] The present disclosure relates to the technical field of solar cells and in particular to a back-contacted solar cell, a photovoltaic module and a photovoltaic system. background

[0003] An interdigitated back-contact solar cell (IBC cell) is an efficient solar cell technology. The positive and negative metal electrodes of the IBC cell are arranged interdigitously on the unilluminated side of the cell, so the front of the cell is not shielded by a metal grid. This design maximizes the illuminated area, reduces optical losses, and increases short-circuit current and overall efficiency. To prevent direct contact of charge carriers in an n-doped and a p-doped zone, which would prevent effective charge carrier collection, an isolation zone must be placed at the junction between the two zones. As cell size decreases, the n- and p-doped zones are positioned closer together, thus reducing the size of the isolation zone accordingly.However, if the insulation zone is too narrow, it does not provide sufficient insulation protection, increasing the risk of short circuits and reducing the efficiency of the back-contacted cell. Furthermore, in a conventional back-contacted interdigitated cell, a surface passivation layer is typically formed on the unilluminated side to reduce the charge carrier recombination rate and improve the power conversion efficiency. However, the passivation effect of the surface passivation layer in the existing back-contacted interdigitated cell on the unilluminated side is poor, which does not contribute to improving the cell's efficiency. Summary

[0004] The main objective of the present disclosure is to provide a back-contacted solar cell, a photovoltaic module and a photovoltaic system that can improve the insulation performance between differently doped areas on the unilluminated side of a back-contacted solar cell, increase the passivation effectiveness and increase the efficiency of solar energy conversion.

[0005] To achieve the above-mentioned objectives, according to one aspect of the present disclosure, a back-contacted solar cell is provided, comprising first zones, second zones and isolation zones arranged on an unilluminated side of a silicon substrate, wherein the first zone and the second zone are arranged alternately and the isolation zone is located between the first zone and the second zone, wherein the first zone comprises a first doped conductive layer and the second zone comprises a second doped conductive layer, and the first doped conductive layer and the second doped conductive layer have opposite doping types;and wherein one side of the first zone facing the isolation zone has a recessed structure, wherein, if the silicon substrate is an n-doped silicon substrate, the first zone is a p-doped zone, the second zone is an n-doped zone, the side of the p-doped zone facing the isolation zone n1 has recessed structures, the side of the n-doped zone facing the isolation zone n2 has recessed structures, and wherein n1 > n2.;

[0006] In some embodiments, the side of the first zone facing the isolation zone has discontinuous recessed structures; and / or a side of the second zone facing the isolation zone has recessed structures.

[0007] In some embodiments, the side of the second zone facing the isolation zone has discontinuous sunken structures.

[0008] In some embodiments, the recessed structure comprises a first unit zone and a first recessed structure, wherein the first unit zone is arranged around the first recessed structure, and the first recessed structure comprises a depression and a projection arranged in the depression; or wherein the first zone comprises an extension section extending and projecting towards the top of the isolation zone, the recessed structure comprises a second unit zone and a second recessed structure, the second unit zone is arranged around the second recessed structure, the extension zone has the second recessed structure, and the second recessed structure is a blind hole or a punched hole.

[0009] In some embodiments, the height of the projection is less than or equal to the depth of the recess; or the shape of the projection has a pyramidal shape and / or a truncated cone shape; or the silicon substrate has an illuminated side opposite the unilluminated side, the projection comprises the silicon substrate and a passivation layer in a direction in which the illuminated side faces the unilluminated side, and a side wall of the recess comprises the passivation layer.

[0010] In some embodiments, the width of the base of the projection is 0.1 µm to 1.5 µm and the height of the projection is 0.01 µm to 10 µm; or the width of an opening of the recess is 0.1 µm to 2 µm and the depth of the recess is 0.01 µm to 10 µm.

[0011] In some embodiments, the passivation layer of the back-contacted solar cell surrounds the extension section, and the second recessed structure penetrates the extension section and the passivation layer; or the width of the second recessed structure is 0.1 µm to 1.5 µm.

[0012] In some embodiments, several recessed structures form an isolation transition zone, and the width of the isolation transition zone is 5 µm to 30 µm.

[0013] In some embodiments, the width of the insulation transition zone is 10 µm to 15 µm.

[0014] In some embodiments, a tunnel layer of the back-contacted solar cell comprises a first tunnel layer, wherein the first tunnel layer is arranged between the first doped conductive layer and the silicon substrate of the first zone, and the first doped conductive layer, the first tunnel layer, and an edge of the silicon substrate in the first zone all extend toward the center of an opening of the isolation zone to form the extension section, or only the first doped conductive layer extends toward the center of the opening of the isolation zone to form the extension section; and / or the tunnel layer of the back-contacted solar cell further comprises a second tunnel layer, wherein the second tunnel layer is arranged between the second doped conductive layer and the silicon substrate of the second zone;or wherein the passivation layer of the back-contacted solar cell covers the first doped conductive layer, the second doped conductive layer and the insulating zone, and the back-contacted solar cell further comprises a first electrode and a second electrode, wherein the first electrode penetrates the passivation layer to be connected to the first doped conductive layer, and the second electrode penetrates the passivation layer to be connected to the second doped conductive layer.

[0015] In some embodiments, the diameter of the second recessed structure is 1.5 µm to 5 µm; or the length of the extension section is 0.1 µm to 40 µm.

[0016] In some embodiments, the side of the first zone facing the isolation zone comprises a first target zone, wherein the length of the first target zone in an extension direction of the isolation zone is greater than 50 µm, and the first target zone does not include the recessed structure; and the side of the second zone facing the isolation zone comprises a second target zone, wherein the length of the second target zone in the extension direction of the isolation zone is greater than 50 µm, and the second target zone does not include the recessed structure.

[0017] According to a further aspect of the present disclosure, a back-contacted solar cell is provided, comprising: a silicon substrate, wherein the silicon substrate has an illuminated side and an unilluminated side opposite the illuminated side, the unilluminated side comprising first zones and second zones, and the first zone and the second zone are arranged alternately in a first direction, the first zones and the second zones all extending in a third direction, and the third direction intersects the first direction; several first doped conductive layers, wherein the first doped conductive layers are arranged on the first zones and cover at least a portion of the first zones, each first zone is provided with the first doped conductive layer, and first recessed structures are formed on at least a portion of the first doped conductive layers;and several second doped conductive layers, wherein the second doped conductive layers are arranged on the second zones and cover at least a part of the second zones, each second zone is provided with the second doped conductive layer, at least a part of the second doped conductive layers is provided with leakage current-prone contacts extending to the first doped conductive layers, and a part of the leakage current-prone contacts extends into the first recessed structures, wherein the leakage current-prone contacts are in leakage current contact with the first doped conductive layers at least in the first recessed structures.

[0018] In some embodiments, the leakage current-prone contact comprises a first part located in the first recessed structure and a second part resting on a surface of the first doped conductive layer facing away from the silicon substrate, wherein the first part is in leakage current contact with the first doped conductive layer, and a dielectric insulating layer is arranged between the second part and the first doped conductive layer; or the second part is in leakage current contact with the surface of the first doped conductive layer facing away from the silicon substrate;or wherein, in the first direction, the leakage current-prone contact extends along a side face 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, wherein the leakage current-prone contact also forms a leakage current contact on the side face of the first doped conductive layer; or wherein, in the first direction, there is a first predetermined distance between the first recessed structure and the side face of the first doped conductive layer, wherein the first predetermined distance is 10 µm to 200 µm; or wherein, 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.

[0019] In some embodiments, the ratio of the length of the first recessed structure in the third direction to the length of the first recessed structure in the first direction is greater than or equal to 2.

[0020] In some embodiments, the first doped conductive layer has a first side face and a second side face that are opposite each other in the first direction, wherein the first recessed structure does not penetrate the first side face and the second side face, and the first doped conductive layers are arranged on both sides of the first recessed structure in the first direction; or the first doped conductive layer has the first side face and the second side face that are opposite each other in the first direction, wherein the first recessed structure penetrates at least one of the first side face and the second side face;or wherein the first recessed structure completely penetrates the first doped conductive layer in one thickness direction of the first doped conductive layer, such that the silicon substrate is exposed at the first recessed structure, and the leakage current-prone contact covers the exposed silicon substrate as well as at least parts of a side face of the first recessed structure; or 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 leakage current-prone contact covers at least parts of a bottom of the first recessed structure and at least parts of the side face of the first recessed structure;or wherein the first recessed structure completely penetrates the first doped conductive layer in the thickness direction of the first doped conductive layer and forms a trench in the silicon substrate, wherein the penetration depth of the trench in a thickness direction of the silicon substrate is 1 µm to 6 µm; or wherein the first recessed structure completely penetrates the first doped conductive layer in the thickness direction of the first doped conductive layer and forms a trench in the silicon substrate, wherein the first doped conductive layers have second projections on both sides of the trench extending to a top surface of the trench, and the leakage current-prone contact surrounds at least one of the second projections and extends into the first recessed structure;or wherein the first indented structure completely penetrates the first doped conductive layer in the thickness direction of the first doped conductive layer and forms a trench in the silicon substrate, wherein a second predetermined distance exists between the first doped conductive layers on both sides of the trench and an edge of the trench in the first direction.

[0021] In some embodiments, an internal extension layer is formed in a part of the silicon substrate corresponding to the first zone, wherein a polarity of the internal extension layer corresponds to a doping type of the first doped conductive layer, and the first recessed structure does not penetrate the internal extension layer, and the leakage current-prone contact is in leakage current contact with a surface of the internal extension layer facing away from the silicon substrate; or wherein the first recessed structure penetrates the internal extension layer, and the leakage current-prone contact is in leakage current contact with a side face of the internal extension layer that is exposed at the first recessed structure.

[0022] In some embodiments, the second zone is a groove formed in the silicon substrate, wherein the first doped conductive layer comprises a first projection extending to a top surface of the groove, and the leakage current-prone contact runs along a side surface of the groove, surrounds the first projection, extends onto the first doped conductive layer, and reaches into the first recessed structure; or the second zone is a groove formed in the silicon substrate, wherein the first doped conductive layer does not completely cover the first zone, such that an exposed zone of the first zone exists between the first doped conductive layer and the groove, and the leakage current-prone contact extends into and covers the exposed zone;or a step structure is formed at an edge of the side of the first doped conductive layer facing the groove, wherein the leakage current-prone contact covers the step structure, and the leakage current-prone contact is in leakage current contact with the first doped conductive layer at the step structure.;

[0023] In some embodiments, a dielectric layer is arranged on an area in the first recessed structure that is covered by the leakage current-prone contact, wherein the leakage current-prone contact covers the dielectric layer, and the leakage current-prone contact is in leakage current contact with the first doped conductive layer in the first recessed structure above the dielectric layer.

[0024] In some embodiments, the size of the second predetermined distance is 0.3 µm to 50 µm.

[0025] 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, with a penetration depth of the first recessed structure being 20 nm to 200 nm; or several first recessed structures are arranged on a single first doped conductive layer, spaced apart in the third direction.

[0026] In some embodiments, the distance between two adjacent first recessed structures in the third direction is 1 cm to 10 cm; or the multiple first recessed structures are arranged in at least two columns in the third direction.

[0027] In some embodiments, the distribution density of the first recessed structures in the back-contacted solar cell is 0.01 pieces / cm². 2 up to 1.5 pieces / cm² 2; or, in the case of a single first recessed structure, the leakage current contact area between the leakage current-prone contact and the first doped conductive layer is 1.2 µm² 2 up to 1500 µm 2 ; or in the back-contacted solar cell, the ratio of the total area on which all leakage current-prone contacts 31 are in contact with the first doped conductive layers 161 to the area of ​​the unilluminated side of the back-contacted solar cell is in the range of 4.5 × 10 -8 up to 1.5 × 10 -5 .

[0028] In some embodiments, zones in the first doped conductive layer and the second doped conductive layer that are not covered by the leakage current-prone contacts are leakage current-free zones, and zones in the first doped conductive layer and the second doped conductive layer that are not part of the leakage current-free zones are leakage current-prone zones; and within an equal unit length, the number of first recessed structures in the leakage current-free zones is greater than the number of first recessed structures in the leakage current-prone zones.

[0029] According to another aspect of the present disclosure, a photovoltaic module is provided which includes one of the back-contacted solar cells described above.

[0030] According to another aspect of the present disclosure, a photovoltaic system is provided which includes the photovoltaic module described above.

[0031] The embodiments of the present disclosure have the following positive effects: 1. In the present disclosure, the side of the first region on the unilluminated side of the backside contact cell, which is located near the insulation zone, is provided with a recessed structure to improve the insulating effect of the first and second zones through the insulation zone. In addition, the recessed structure increases the size of a contact area between the first zone and the subsequently applied passivation layer, thereby improving the passivation effect. 2. In the present disclosure, the side of the second region on the unilluminated side of the backside contact cell, which is located near the insulation zone, is provided with a recessed structure to improve the insulating effect of the first and second zones through the insulation zone. Additionally, the recessed structure increases the size of the contact area between the second zone and the subsequently applied passivation layer, thereby improving the passivation effect. 3. In the present disclosure, the first recessed structure comprises the depression and the projection arranged therein, wherein the bottom of the depression is formed on the silicon substrate to improve the insulating effect between the first and the second zone; and the contact area with the subsequently applied passivation layer is further increased by the arrangement of the projection, thereby further improving the overall passivation performance. 4. In the present disclosure, the edges of the first zone and the isolation zone are provided with an extension section that extends to and projects from the top of the isolation zone, such that the isolation zone has a small opening and a large interior space. This reduces the exchange of plasma and outside air during the subsequent deposition of the passivation layer. The extension section is provided with a second recessed structure that penetrates the extension section, thereby improving the isolation passivation performance of the extension section. Brief description of the drawings

[0032] The drawings, which form part of this disclosure, serve to enhance understanding of this disclosure. Schematic examples and descriptions thereof serve to illustrate this disclosure and do not constitute an impermissible limitation of this disclosure. In the drawings: Fig. Figure 1 is a first schematic structural diagram of a back-contacted solar cell described in the present disclosure; Fig. 2 is a 3D micrograph of an unilluminated side of a back-contacted solar cell described in the present disclosure; Fig. Figure 3 is a schematic structural diagram of a first sunken structure provided in an embodiment of the present disclosure; Fig.Figure 4 is a schematic diagram of the size of a first sunken structure provided in an embodiment of the present disclosure; Fig. Figure 5 is a schematic structural diagram of a second sunken structure provided in an embodiment of the present disclosure; Fig. Figure 6 is an electron microscopic representation of a sunken structure provided in an embodiment of the present disclosure; Fig. Figure 7 is an electron microscopic representation of a first sunken structure provided in an embodiment of the present disclosure; Fig. Figure 8 is a second schematic structural diagram of a back-contacted solar cell described in the present disclosure; Fig.Figure 9 is a schematic structural diagram of an embodiment of a back-contacted solar cell in the present disclosure, wherein an extension section is provided with a second recessed structure; Fig. Figure 10 is a schematic structural diagram of a further embodiment of a back-contacted solar cell according to the present disclosure, in which an extension section has a second recessed structure; Fig. Figure 11 is a schematic representation of an enlarged structure of a hole area in Fig. 10; Fig. Figure 12 is a schematic structure diagram of an embodiment of a back-contacted solar cell according to the present disclosure, wherein first zones, first tunnel layers and first doped conductive layers are all provided with extension sections; Fig.Figure 13 is a schematic diagram of the microstructure of a further embodiment of a back-contacted solar cell according to the present disclosure, wherein first zones, first tunnel layers and first doped conductive layers are all provided with extension sections; Fig. Figure 14 is a schematic structure diagram of an embodiment of a back-contacted solar cell according to the present disclosure, in which only first doped conductive layers are provided with extension sections; Fig. Figure 15 is a schematic diagram of the microstructure of a further embodiment of a back-contacted solar cell according to the present disclosure, in which only first doped conductive layers are provided with extension sections; Fig.16 is a schematic structural diagram of a further embodiment of a back-contacted solar cell according to the present disclosure, in which only first doped conductive layers are provided with extension sections; and Fig. Figure 17 is a schematic diagram of the microstructure of a further embodiment of a back-contacted solar cell according to the present disclosure, in which only first doped conductive layers are provided with extension sections; Fig. Figure 18 shows a schematic diagram of the modules of a photovoltaic system according to an embodiment of the present disclosure; Fig. 19 is a schematic diagram of the modules of a cell module provided in an embodiment of the present disclosure; Fig.Figure 20 is a schematic diagram of a planar structure of a back-contacted solar cell provided in an embodiment of the present disclosure; Fig. 21 is a schematic sectional view of the back-contacted solar cell made of Fig. 20 along a line IV-IV; Fig. 22 is another schematic sectional view of a back-contacted solar cell according to an embodiment of the present disclosure; Fig. 23 is another schematic sectional view of a back-contacted solar cell according to an embodiment of the present disclosure; Fig. Figure 24 is a schematic diagram of the arrangement and structure of a first recessed structure in a back-contacted solar cell provided in an embodiment of the present disclosure; Fig.Figure 25 is a schematic diagram of another planar structure of a back-contacted solar cell provided in an embodiment of the present disclosure; Fig. Figure 26 is a schematic diagram of another arrangement and structure of a first recessed structure in a back-contacted solar cell provided in an embodiment of the present disclosure; Fig. 27 is another schematic sectional view of a back-contacted solar cell according to an embodiment of the present disclosure; Fig. Figure 28 is another schematic sectional view of a back-contacted solar cell according to an embodiment of the present disclosure; Fig. Figure 29 is another schematic sectional view of a back-contacted solar cell according to an embodiment of the present disclosure; Fig.Figure 30 is another schematic sectional view of a back-contacted solar cell according to an embodiment of the present disclosure; and Fig. Figure 31 is another schematic sectional view of a back-contacted solar cell according to an embodiment of the present disclosure. Detailed description of the embodiments

[0033] It should be noted that the following detailed descriptions are exemplary and serve to further describe the present disclosure. Unless otherwise stated, all technical and scientific terms used herein have the same meanings that are generally known to a person skilled in the art in the field to which the present disclosure belongs.

[0034] It should be noted that the terms used herein serve only to describe certain embodiments and do not limit the exemplary embodiments according to this disclosure. Unless the context clearly requires otherwise, the singular form includes the plural form. Furthermore, it should be understood that the terms "contain" and / or "comprise" in this specification refer to the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] It should be noted that terms such as "firstly" and "secondly," etc., in the description, claims, and the above drawings of the present disclosure serve to distinguish similar objects and do not necessarily describe a particular sequence or hierarchy. It is understood that, under appropriate circumstances, the data thus used are interchangeable to describe the embodiments of the present disclosure. Furthermore, the terms "including" and "have," and all variations thereof, do not include exclusive inclusions. For example, processes, methods, systems, products, or devices comprising a series of steps or units are not necessarily limited to the steps or units explicitly listed, but may also include other steps or units not explicitly listed or inherent in such processes, methods, products, or devices.

[0036] It should be noted that an element (e.g., a layer, a film, an area, or a substrate) described as lying "on" another element may either lie directly on the other element or be connected by an intervening element. Likewise, an element described in the description and claims as "connected" to another element may either be directly connected to it or connected to it via a third element.

[0037] As explained in the background of the technology, when using a back-contacted solar cell according to the prior art, if an object in the environment shields a cell, a hotspot phenomenon will occur on the shielding cell. At relatively high temperatures, the packaging adhesive film of a module tends to carbonize, which can even cause a fire. In order to solve at least one of the following problems in the prior art—low ​​hotspot resistance, low insulation performance of differently doped zones on an unilluminated side of the back-contacted solar cell, low power conversion efficiency of the solar cell, low power output of the back-contacted solar cell, and possible confusion in identification—the embodiments of the present disclosure describe a back-contacted solar cell, a photovoltaic module, and a photovoltaic system.The back-contacted solar cell comprises first zones and second zones arranged on an unilluminated side of a silicon substrate, wherein the first zone and the second zone are arranged alternately, and the first zone has a first doped conductive layer, and the second zone has a second doped conductive layer, and the first doped conductive layer and the second doped conductive layer have opposite doping types.

[0038] The technical solutions in the embodiments of the present disclosure are clearly and completely described below in conjunction with the drawings in the exemplary embodiments of the present disclosure.

[0039] In some optional embodiments, a back-contacted solar cell comprises first zones and second zones arranged on an unilluminated side of a silicon substrate, wherein the first and second zones are arranged alternately, and the first zone has a first doped conductive layer, and the second zone has a second doped conductive layer, and the first and second doped conductive layers have opposite doping types. The back-contacted solar cell further comprises isolation zones, wherein the isolation zone is located between the first and second zones. The side of the first zone facing the isolation zone is provided with a recessed structure.

[0040] As in Fig.As shown in Figure 1, this disclosure provides a back-contacted solar cell comprising first zones 13, second zones 14 and isolation zones 15 arranged on an unilluminated side 12 of a silicon substrate 1, wherein the first zones 13 and the second zones 14 are arranged alternately, and the first zone 13 comprises a first doped conductive layer 161, and the second zone 14 comprises a second doped conductive layer 162, and the first doped conductive layer 161 and the second doped conductive layer 162 have opposite doping types.For example, the first doped conductive layer can have the same or an opposite doping type as the silicon substrate, and the first doped conductive layer and the second doped conductive layer have opposite doping types, therefore, on the unilluminated side of the back-contacted solar cell, the first zones 13 and the second zones 14 have opposite conductivity types, and the isolation zones are arranged between the first zones and the second zones with opposite conductivity types, so that the spaced-apart first and second zones can prevent a short circuit through contact between the first zones and the second zones.

[0041] The side of the first zone 13, which is close to the isolation zone 15, is provided with a sunken structure 17.

[0042] In contrast to the prior art, where the isolation zone is located between the first and second zones, the present disclosure provides the side of the first zone near the isolation zone with an additional recessed structure. This further improves the isolation between the first and second zones. Due to the reduction in cell size, the distance between the differently doped zones is also reduced, which increases the requirements for the isolation zone between the first and second zones. The recessed structure enhances the insulating effect for the same width of the isolation zone. Furthermore, the recessed structure improves light absorption, reduces light reflection, and leads to a greater generation of charge carriers in the silicon substrate, thus increasing the cell's efficiency.Furthermore, the arrangement of the recessed structure increases the contact area between the first zone and a passivation layer subsequently applied to its surface, thereby improving the surface passivation effect of the first zone by the passivation layer and further increasing the efficiency of the back-contacted solar cell.

[0043] In a preferred embodiment, as in Fig.As shown in Figure 2, the side of the first zone 13 near the isolation zone 15 is provided with discontinuous recessed structures 17. Several of these recessed structures form an isolation transition zone 171. The discontinuous arrangement of the recessed structures further improves the isolation effect of the first and second zones. The width L of the isolation transition zone 171 can be selected, in particular, between 5 µm and 30 µm, for example 6 µm, 8 µm, 10 µm, 15 µm, 20 µm, or 25 µm, but is not limited to this. Preferably, the width L of the isolation transition zone 171 is from 10 µm to 15 µm. By controlling the width range of the insulation transition zone 171, no negative effects are produced on the intrinsic performance of the first zone 13 and the second zone 14, while at the same time improving the insulation performance, thereby ensuring the collection and transfer effects of the charge carriers.

[0044] Accordingly, the side of the second zone adjacent to the isolation zone can also be provided with a recessed structure whose function is the same as that on the side of the first zone adjacent to the isolation zone. In a preferred embodiment, the side of the second zone adjacent to the isolation zone is provided with discontinuous recessed structures. Likewise, several discontinuous recessed structures form an isolation transition zone with a width of 5 µm to 30 µm, preferably 10 µm to 15 µm.

[0045] As in Fig. 1, Fig. 3, Fig. 6 and Fig.As shown in Figure 7, the recessed structure 17 comprises a first unit zone 172 and a first recessed structure 173. The first unit zone 172 encloses the first recessed structure 173, which has a depression 174 and a projection 175 located therein. The silicon substrate 1 has an illuminated side 11 and an unilluminated side 12, which are opposite each other. In a direction in which the illuminated side 11 faces the unilluminated side 12, the projection 175 includes the silicon substrate 1 and a passivation layer 18, and the side wall of the depression 174 also includes the passivation layer 18, and the first unit zone 172 includes the silicon substrate 1, a tunnel layer 19, the doped conductive layer 16 and the passivation layer 18, and the silicon substrate 1, the tunnel layer 19, the doped conductive layer 16 and the passivation layer 18 are stacked sequentially.It should be noted that in the first zone 13, the doped conductive layer 16 belonging to the first unit zone 172 is the first doped conductive layer 161; and in the second zone 14, the doped conductive layer 16 belonging to the first unit zone 172 is the second doped conductive layer 162. By forming the first recessed structure 173 in the first zone 13 and / or the second zone 14, the bottom of the depression 174 of the first recessed structure 173 is positioned on the silicon substrate 1, so that the insulating effect of the first zone 13 and the second zone 14 can be improved, and the passivation layer 18 covers the top of the first recessed structure 173, and by arranging the projection 175, the contact area between the passivation layer 18 and the first zone 13 or the second zone 14 is further increased, thereby further improving the overall passivation performance.

[0046] The application of the passivation layer 18 reduces the recombination of surface charge carriers. The passivation layer 18 covers the first zone 13, the second zone 14, and the isolation zone 15, passivating the side of the first doped conductive layer 161 facing away from the silicon substrate, as well as the side of the second doped conductive layer 162 facing away from the silicon substrate 1. This reduces the recombination rate of charge carriers on both sides, further improving the efficiency of the back-contacted solar cell. The passivation layer 18 can consist of one or more layers of aluminum oxide, silicon nitride, silicon oxide, and / or silicon oxynitride.Preferably, the passivation layer 18 consists of an aluminum oxide layer and a silicon nitride layer arranged one after the other.

[0047] The tunneling layer can be divided into a first and a second tunneling layer; the first tunneling layer is located between the silicon substrate in the first zone and the first doped conductive layer; and the second tunneling layer is located between the silicon substrate in the second zone and the second doped conductive layer. The tunneling effect allows most charge carriers to penetrate the doped conductive layer, while blocking the passage of minority charge carriers. As a result, most charge carriers are transported through the first and second doped conductive layers and captured by the corresponding electrodes. This reduces the recombination rate of charge carriers of different conductivity types at the surface of the first and second zones, respectively, enabling the selective collection of charge carriers and thus improving the efficiency of the back-contacted solar cell.The first tunnel layer and the second tunnel layer can each consist of one or more of the following layers: a silicon oxide layer, a silicon carbide layer, a silicon nitride layer, and an aluminum oxide layer, wherein the first tunnel layer and the second tunnel layer are preferably silicon oxide layers.

[0048] In a preferred embodiment, the height of the projection is less than or equal to the depth of the depression; even better is if the height of the projection is less than the depth of the depression to facilitate the deposition of the subsequent passivation layer. The projection can, in particular, have the shape of a pyramid and / or a truncated cone.

[0049] It can be assumed that both the size of the projection and the size of the depression influence the insulation effect and the passivation performance. As in Fig.As shown in Figure 4, the width D1 at the base of the projection has a certain influence on the insulation effect and the passivation performance. The width D1 of the base of the projection is between 0.1 µm and 1.5 µm, and the height H1 is between 0.01 µm and 10 µm. If H1 is less than 0.01 µm, there is a risk of short circuits, which reduces the yield. If H1 is greater than 10 µm, the coverage of the subsequent passivation layer is impaired, thus reducing the passivation effect. The width D2 at the opening of the depression is between 0.1 µm and 2 µm, and the depth H2 of the depression is between 0.01 µm and 10 µm. If D2 is less than 0.1 µm, the passivation effect is impaired. If D2 is greater than 10 µm, a copper residue is formed, which leads to leakage. The passivation effect is impaired by excessively high or low H2 values.For H₂ < 0.01 µm, the hydrogen passivation of the subsequently deposited passivation layer on the silicon substrate is weakened, thus reducing the yield. Conversely, if H₂ is larger than 10 µm, the recombination of charge carriers on the surface of the silicon substrate increases. By limiting the size of the protrusion and depression, the passivation and insulation performance of the cell can be improved without impairing charge carrier collection and transport. Furthermore, by controlling the size of the protrusion and depression as described in this disclosure, the subsequent formation of a passivation layer on the back side is facilitated, and the passivation layer can completely fill the first indented structure, thereby improving the film formation quality of the passivation layer.

[0050] As in Fig. 1, Fig. 5 and Fig.As shown in Figure 6, the first zone 13 comprises an extension section 163 that extends over and projects from the top of the insulation zone 15. The recessed structure 17 comprises a second unit zone 176 and a second recessed structure 177. The second unit zone 176 surrounds the second recessed structure 177, with the extension section 163 being provided with the second recessed structure 177. The second recessed structure 177 can be a blind hole or a punched hole. For example, as shown in Figure 6. Fig. 5 and Fig. As shown in Figure 6, the second recessed structure 177 penetrates the extension section 163 and forms a pore 178. In this embodiment, the second recessed structure 177 is a punched hole (the pore 178).

[0051] In a preferred embodiment, we in Fig.As shown in Figure 5, the back-contacted solar cell comprises the passivation layer 18, which surrounds the extension section 163. The second recessed structure 177 penetrates the extension section 163 and the passivation layer 18 to form the pore 178. The passivation layer 18 surrounds the extension section 163, thus ensuring passivation performance. In one embodiment, the width D3 of the pore 178 is 0.1 µm to 1.5 µm, for example 0.2 µm, 0.5 µm, 0.8 µm, 1 µm, 1.1 µm, or 1.4 µm, but is not limited to these values.

[0052] In addition to the structures described above, the back-contacted solar cell comprises a front-side passivation layer, a first electrode, and a second electrode. The front-side passivation layer is applied to the front of the silicon substrate, thus preventing shading by metal electrodes. The first electrode penetrates the passivation layer and makes contact with the first doped conductive layer. The second electrode also penetrates the passivation layer and makes contact with the second doped conductive layer. One or more of the metals silver, aluminum, copper, and nickel can be used as materials for the first and second electrodes.

[0053] In a preferred embodiment, the number of recessed structures on the side of the doped zones with a different doping type than the silicon substrate is greater than or equal to the number of recessed structures on the side of the doped zones with the same doping type as the silicon substrate. This improves the guidance of fluid flow in subsequent processes and facilitates the removal of impurities such as metals, which in turn improves the surface quality of the recessed structures. Furthermore, a greater number of recessed structures facilitates the current sensing of an emitter. It can be seen that, in a p-doped silicon substrate, the first doped zone is n-doped and the second is p-doped.The side of the p-doped zone near the isolation zone has n1 recessed structures, and the side of the n-doped zone near the isolation zone has n2 recessed structures, where n1 ≤ n2 and preferably n1 < n2. That is, for a p-doped silicon substrate, the number of recessed structures on the side of the p-doped zone near the isolation zone is less than or equal to the number of recessed structures on the side of the n-doped zone. If the silicon substrate is a p-doped silicon substrate, n1 can be equal to 0.

[0054] Accordingly, in an n-doped silicon substrate, the first doped zone is p-doped, and the second is n-doped. The side of the p-doped zone near the isolation zone has n1 recessed structures, and the side of the n-doped zone has n2, where n1 ≥ n2 and preferably n1 > n2. That is, in an n-doped silicon substrate, the number of recessed structures on the side of the p-doped zone near the isolation zone is greater than or equal to the number of recessed structures on either side of the n-doped zone. The p-doped zone acts as the emitter, and the arrangement of additional recessed structures in the p-doped zone facilitates current flow. If the silicon substrate is an n-doped silicon substrate, n2 can be zero.

[0055] Optionally, to facilitate the transfer and collection of charge carriers and to reduce stress defects and the risk of hidden cracks in the cells, the distance between two adjacent recessed structures 17 on the side of the first zone 13 near the isolation zone 15 can be greater than 100 µm; and / or the distance between two adjacent recessed structures 17 on the side of the second zone 14 near the isolation zone 15 can be greater than 100 µm.

[0056] Optionally, the side of the first zone near the isolation zone includes a first target zone that has a length greater than 50 µm in the direction of the isolation zone and that does not include the recessed structure. Similarly, the side of the second zone near the isolation zone includes a second target zone that has a length greater than 50 µm in the direction of the isolation zone and that does not include the recessed structure.

[0057] Accordingly, the present disclosure further provides a method for manufacturing the back-contacted solar cell, including: S1, Provision of a silicon substrate.

[0058] More precisely, the silicon substrate can be an n-doped silicon substrate or a p-doped silicon substrate, and an unilluminated side of the silicon substrate has first zones and second zones, with the first zone and the second zone arranged alternately.

[0059] S2, Formation of a first doped conductive layer at least in the first zone of the unilluminated side of the silicon substrate and formation of a sunken structure on the surface of the first zone.

[0060] The first doped conductive layer can be located within or on the silicon substrate. Preferably, a first tunnel layer and the first doped conductive layer are located in the first zone on the unilluminated side of the silicon substrate. The first doped conductive layer can be a p-doped or an n-doped conductive layer.

[0061] In a preferred embodiment, the first tunnel layer and the first doped conductive layer are formed on the unilluminated side of the silicon substrate. At least the portion of the first tunnel layer located in the second zone is processed to remove at least that portion of the first tunnel layer in the second zone. Laser direct structuring and wet etching are used for this processing, and a recessed structure is formed on the surface of the processed first doped conductive layer.

[0062] S3, formation of at least a second doped conductive layer in the second zone.

[0063] The second doped conductive layer can be arranged within or on the silicon substrate. Preferably, a second tunnel layer and the second doped conductive layer are arranged in the second zone on the unilluminated side of the silicon substrate, wherein the second doped conductive layer and the first doped conductive layer have opposite doping types.

[0064] In a preferred embodiment, the second tunnel layer and the second doped conductive layer are formed on the unilluminated side of the silicon substrate, and the first doped conductive layer and at least the portion of the second tunnel layer located on the first doped conductive layer are machined to remove at least the portion of the second tunnel layer located on the first doped conductive layer. Laser direct structuring and wet etching are used for the machining, and a recessed structure is formed on the surface of the machined first doped conductive layer.

[0065] S4, Formation of an isolation zone between the first zone and the second zone.

[0066] In a preferred embodiment, the portion of the second tunnel layer located between the first and second zones is processed to remove the section of the second tunnel layer between the first and second zones, thereby forming the isolation zone. Laser direct structuring and wet etching are used for this processing, and a recessed structure is formed on the surface of the processed second doped conductive layer.

[0067] Passivation layers are then deposited on the first doped conductive layer, on the second doped conductive layer and on the insulating zone 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.

[0068] The present disclosure is described in more detail below with reference to specific exemplary embodiments: Example 1

[0069] The present embodiment relates to a back-contacted solar cell with p-doped zones, n-doped zones, and isolation zones arranged on the back side of an n-doped silicon substrate. The p-doped and n-doped zones are arranged alternately, and the isolation zone is located between them. The p-doped zone has a p-doped conductive layer, and the n-doped zone has an n-doped conductive layer. The side of the p-doped zone facing the isolation zone is provided with a recessed structure.

[0070] The recessed structure comprises a first recessed structure and a first unit zone surrounding the first recessed structure. The first recessed structure has a depression and a projection located therein. Specifically, in the direction where the illuminated side faces the unilluminated side, the projection comprises the silicon substrate and a passivation layer, and the side wall of the depression comprises the passivation layer. The first unit zone comprises the silicon substrate, a tunnel layer, the p-doped conductive layer, and the passivation layer, stacked in that order. The width of the projection at the bottom is 0.1 µm to 1.5 µm, and the height of the projection is 0.01 µm to 10 µm. The opening width of the depression is 0.1 µm to 2 µm, and the depth of the depression is 0.01 µm to 10 µm. The projection is pyramidal in shape. Example 2

[0071] The present embodiment relates to a back-contacted solar cell with p-doped zones, n-doped zones, and isolation zones arranged on the back side of an n-doped silicon substrate. The p-doped and n-doped zones are arranged alternately, and the isolation zone is located between them. The p-doped zone has a p-doped conductive layer, and the n-doped zone has an n-doped conductive layer. The side of the p-doped zone facing the isolation zone is provided with a recessed structure.

[0072] The recessed structure comprises a first recessed structure and a first unit zone that surrounds the first recessed structure. The first recessed structure has a depression and a projection within it. Specifically, in the direction where the illuminated side of the silicon substrate faces the unilluminated side, the projection includes the silicon substrate and a passivation layer, and the side wall of the depression includes the passivation layer. The first unit zone comprises the silicon substrate, a tunnel layer, the p-doped conductive layer, and the passivation layer, stacked in that order. The width of the projection at the bottom is 0.3 µm to 1.2 µm, the height of the projection is 0.05 µm to 2 µm, the opening width of the depression is 0.5 µm to 2 µm, and the depth of the depression is 0.1 µm to 5 µm. The protrusion is pyramid-shaped. Example 3

[0073] The present embodiment relates to a back-contacted solar cell with p-doped zones, n-doped zones, and isolation zones arranged on the back side of an n-doped silicon substrate. The p-doped and n-doped zones are arranged alternately, and the isolation zone is located between them. The p-doped zone has a p-doped conductive layer, and the n-doped zone has an n-doped conductive layer. The side of the p-doped zone facing the isolation zone is provided with a recessed structure.

[0074] The recessed structure comprises a first recessed structure and a first unit zone that surrounds the first recessed structure. The first recessed structure has a depression and a projection within it. Specifically, in the direction where the illuminated side of the silicon substrate faces the unilluminated side, the projection includes the silicon substrate and a passivation layer, and the side wall of the depression includes the passivation layer. The first unit zone comprises the silicon substrate, a tunnel layer, the p-doped conductive layer, and the passivation layer, stacked in that order. The width of the projection at the bottom is 0.3 µm to 1.2 µm, the height of the projection is 0.05 µm to 2 µm, the opening width of the depression is 0.5 µm to 2 µm, and the depth of the depression is 0.1 µm to 5 µm. The protrusion is pyramid-shaped.

[0075] The p-doped zone comprises an extensional section that extends to and protrudes from the top of the isolation zone. The recessed structure further includes a second recessed structure and a second unit zone arranged around the second recessed structure. The second recessed structure penetrates the extensional section, forming a pore with a width between 0.1 µm and 1.5 µm. Example 4

[0076] The present embodiment relates to a back-contacted solar cell with p-doped zones, n-doped zones, and isolation zones arranged on the back side of an n-doped silicon substrate. The p-doped and n-doped zones are arranged alternately, and the isolation zone is located between them. The p-doped zone has a p-doped conductive layer, and the n-doped zone has an n-doped conductive layer. The side of the p-doped zone facing the isolation zone is provided with a recessed structure.

[0077] The recessed structure comprises a first recessed structure and a first unit zone that surrounds the first recessed structure. The first recessed structure has a depression and a projection within it. Specifically, in the direction where the illuminated side of the silicon substrate faces the unilluminated side, the projection includes the silicon substrate and a passivation layer, and the side wall of the depression includes the passivation layer. The first unit zone comprises the silicon substrate, a tunnel layer, the p-doped conductive layer, and the passivation layer, stacked in that order. The width of the projection at the bottom is 0.3 µm to 1.2 µm, the height of the projection is 0.05 µm to 2 µm, the opening width of the depression is 0.5 µm to 2 µm, and the depth of the depression is 0.1 µm to 5 µm. The protrusion is pyramid-shaped.

[0078] The p-doped zone comprises an extensional section that extends to and protrudes from the top of the isolation zone. The recessed structure further includes a second recessed structure and a second unit zone arranged around the second recessed structure. The second recessed structure penetrates the extensional section, forming a pore with a width between 0.5 µm and 0.8 µm. Example 5

[0079] The present embodiment relates to a back-contacted solar cell with p-doped zones, n-doped zones, and isolation zones arranged on the back side of an n-doped silicon substrate. The p-doped and n-doped zones are arranged alternately, and the isolation zone is located between the p-doped and n-doped zones. The p-doped zone has a p-doped conductive layer, and the n-doped zone has an n-doped conductive layer.

[0080] The side of the p-doped zone near the isolation zone is provided with a sunken structure.

[0081] The recessed structure comprises a first recessed structure and a first unit zone that surrounds the first recessed structure. The first recessed structure has a depression and a projection within it. Specifically, in the direction where the illuminated side of the silicon substrate faces the unilluminated side, the projection includes the silicon substrate and a passivation layer, and the side wall of the depression includes the passivation layer. The first unit zone comprises the silicon substrate, a tunnel layer, the p-doped conductive layer, and the passivation layer, stacked in that order. The width of the projection at the bottom is 0.3 µm to 1.2 µm, the height of the projection is 0.05 µm to 2 µm, the opening width of the depression is 0.5 µm to 2 µm, and the depth of the depression is 0.1 µm to 5 µm. The protrusion is pyramid-shaped.

[0082] The p-doped zone comprises an extensional section that extends to and protrudes from the top of the isolation zone. The recessed structure further includes a second recessed structure and a second unit zone arranged around the second recessed structure. The second recessed structure penetrates the extensional section, forming a pore with a width between 0.5 µm and 0.8 µm.

[0083] The side of the n-doped zone facing the isolation zone also has a first indentation. The number of first indentations in the n-doped zones is lower than the number of first indentations in the p-doped zones. The remaining features are the same as in embodiment 1.

[0084] After electrode printing and sintering of the back-contacted solar cells produced in embodiments 1 to 5, a heat treatment is carried out to obtain finished solar cells. The efficiency of the finished solar cell is then measured, and the results are listed in the following table. Power conversion efficiency Example 1 26,68% Example 2 26,72% Example 3 26,75% Example 4 26,77% Example 5 26,79%

[0085] The back-contacted solar cell described in the present disclosure comprises a silicon substrate, a first tunnel layer, and a first doped conductive layer. The silicon substrate has a front and back side facing each other. The back side is provided with several first and several second zones, the first and second zones being arranged alternately and sequentially in a first direction. Adjacent first and second zones are separated from each other by an insulating zone. The first doped conductive layer is located on the silicon substrate of the first zone. The first tunnel layer is located between the first doped conductive layer and the silicon substrate of the first zone.The first doped conductive layer, the tunnel layer, and an edge of the silicon substrate of the first zone all extend toward the center of the isolation zone opening, forming the extension section. Alternatively, only the first doped conductive layer extends toward the center of the isolation zone opening, forming the extension section, which is then equipped with a second recessed structure. The arrangement of the extension section reduces the size of the isolation zone opening. This reduces plasma-to-environment exchange during the subsequent deposition of the passivation layer and achieves a partial distribution of the hydrogen content within the passivation layer. This results in a lower mobile oxygen content in the passivation layer within the isolation zone and a higher mobile oxygen content in the other zones.This effectively improves the passivation and damping effects. Additionally, the arrangement of the second recessed structure in the extension section facilitates the detection and alignment of subsequent processes, while not impairing the passivation of a polycrystalline silicon film, thus ensuring the efficiency of the solar cell. Example 6

[0086] As in Fig. 8 to Fig.As shown in Figure 17, an embodiment of the present disclosure provides a back-contacted solar cell comprising: a silicon substrate 1, wherein the silicon substrate 1 has an illuminated side 11 and an unilluminated side 12 opposite each other, the unilluminated side 12 being provided with several first zones 13 and several second zones 14, the first zone 13 and the second zone 14 being arranged sequentially and alternately in a first direction, each adjacent first zone 13 and second zone 14 being separated from each other by an isolation zone 15; first doped conductive layers 161 arranged on the silicon substrate 1 of the first zones 13; and first tunnel layers 200 arranged between the first doped conductive layers 161 and the silicon substrate 1 of the first zones 13; wherein the edges of the first doped conductive layers 161, the first tunneling layers 200 and the silicon substrate 1 of the first zones 13 all extend towards the center of the opening 15 of the isolation zone to form the extension section; or, only the first doped conductive layers 161 extend towards the center of the opening 15 of the isolation zone to form the extension section; and the extension sections exhibit second sunken structures 177.

[0087] The silicon substrate 1 has the form of a plate or sheet, and the illuminated side 11 and the unilluminated side 12 are opposite each other.

[0088] Optionally, in some embodiments, the silicon substrate 1 is an n-doped silicon wafer and in other embodiments a p-doped silicon wafer, the choice being non-restrictive. The n-doped silicon wafer is obtained by doping an intrinsic semiconductor with a pentavalent element (e.g., phosphorus, arsenic, bismuth, or the like), and the p-doped silicon wafer by adding a trivalent element (e.g., boron, gallium, indium, or the like) to the intrinsic semiconductor. Repetitions of these specifications are not given.

[0089] During the implementation, several spaced-apart isolation zones 15 are formed on the unilluminated side 12 of the silicon substrate 1, and the unilluminated side 12 is subdivided by the isolation zones 15 into first zones 13 and several second zones 14, which are arranged sequentially and alternately. That is, each adjacent first zone 13 and second zone 14 are separated from each other by the isolation zone 15.

[0090] In some optional embodiments, the first direction is a horizontal transverse direction. As in Fig. As shown in Figure 8, the extension direction of a line segment L is the first direction, and the first zones 13 and the second zones 14 are arranged alternately in the horizontal transverse direction of the silicon substrate 1, and the isolation zones 15 extend in the longitudinal direction to separate the adjacent first zones 13 and second zones 14 from each other.

[0091] In this implementation, the first zones 13 and the second zones 14 are zones with opposite doping types to the solar cell. For example, the silicon substrate 1 is an n-doped silicon wafer. A trivalent element is deposited on this n-doped silicon wafer to create an emitter zone. This emitter zone can, in this case, be described as a p + -layer is considered, and analogously, a five-valent element is doped on the basis of an n-doped silicon wafer to obtain a doped diffusion layer, which in this case is referred to as an n + -layer can be considered. If the first zone 13 p + -layers are, are the second zones 14 n + -layer. Similarly, if the first zone 13 n + -layers are, are the second zones 14 p + -layer.

[0092] The first tunnel layers 200 and the first doped conductive layers 161 are stacked on the first zones 13, with the edges of the first tunnel layers 200, the first doped conductive layers 161, and the silicon substrate 1 of the first zones 13 all extending towards the center of the opening 15 of the isolation zone to form the extension section. That is, the first tunnel layers 200, the first doped conductive layers 161, and the silicon substrate 1 of the first zones 13 all project towards the opening 15 of the isolation zone to form the extension section, so that the isolation zone 15 forms a recessed structure with small openings and large interiors.

[0093] In this process, the isolation zones 15 and the extension sections on the silicon substrate 1 can be formed in a combined grooving and etching mode. For example, an opening extending in a second direction is first created on the silicon substrate 1 in a mechanical or chemical etching mode, with the second direction being perpendicular to the first direction. Subsequently, the opening is etched in an acid or alkaline etching mode.Since the corrosion resistance of the first tunnel layers 200 and the first doped conductor layers 161 differs from the corrosion resistance of the silicon substrate 1—in general, the corrosion resistance of the first tunnel layers 200 and the first doped conductor layers 161 is better than that of the silicon substrate 1—when the opening is etched in acid or alkaline etching mode, the silicon substrate 1 is etched rapidly, while the first tunnel layers 200 and the first doped conductor layers 161 are etched slowly or not at all. This reduces the etch rate of the zones of the silicon substrate 1 near the first tunnel layers 200 and the first doped conductor layers 161. Consequently, the edges of the silicon substrate 1 of the first zones 13 protrude near the isolation zones 15 and form the first expansion regions 140 of the silicon substrate 1 of the first zones 13.The first doped conductive layers 161 and the first tunnel layers 200 protrude from the isolation zones 15 and form the second extension sections 310 (see . Fig. 8) By forming recessed zones (i.e., the isolation zones 15) with small openings and large interiors, the exchange between plasma and environment is reduced during the subsequent deposition of the passivation layers. It is evident that in this embodiment, the extension sections formed by extending the edges of the first doped conductive layers 161, the first tunnel layers 200, and the silicon substrate 1 of the first zones 13 toward the center of the opening 15 of the isolation zone comprise the first extension sections 140 and the second extension sections 310, as shown in Fig. 8 shown.

[0094] In some embodiments, when acid or alkali etching the silicon substrate 1, it is etched quickly, whereby the etch rate of the areas of the silicon substrate 1 near the first tunnel layers 200 and near the first doped conductive layers 161 is reduced.

[0095] As a result, the side walls of the silicon substrate 1 taper to conical walls in the first zones 13 and form the first extension sections 140. At the same time, the edges of the first tunnel layers 200 and the first doped conductive layers 161 protrude near the isolation zones 15 and form the second extension sections 310 (see Fig. 12 and Fig. 13). This creates sunken zones with small openings and large interior spaces.

[0096] In some possible embodiments, only the first doped conductive layers 161 have the second extension sections 310. For example, an opening in the second direction is first formed on the silicon substrate 1 by mechanical processing or chemical etching. This opening is then further etched by acid or alkali etching. The side walls of the silicon substrate 1 of the first zones 13 become vertical walls. The areas of the first tunnel layers 200 and the first doped conductive layers 161 near the isolation zones 15 protrude. The protruding first tunnel layers 200 are subsequently removed by a cleaning process, so that only the protruding areas of the first doped conductive layers 161 remain. That is, only the first doped conductive layers 161 extend towards the center of the opening 15 of the isolation zone and thus form the second extension sections 310.This creates the sunken areas with the small openings and the large interior spaces, as in . Fig. 14 and Fig. Figure 15 shows that in this embodiment the extension sections formed by the first doped conductive layers 161, which extend towards the center of the opening 15 of the insulation zone, are the second extension sections 310, as shown in Fig. 14 and Fig. 15 shown.

[0097] Optionally, the extension section allows the isolation zone 15 to form a structure with a small opening and a large interior. Therefore, the length of the extension section must be within a specific, appropriate range. For example, the length of the extension section can be between 0.1 µm and 40 µm, such as 0.2 µm, 0.3 µm, 25 µm, 30 µm, 35 µm, or any value between 0.1 µm and 40 µm. Preferably, the length of the expansion section is between 0.5 µm and 20 µm, for example 0.6 µm, 0.7 µm, 1 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 11 µm, 15 µm, or any value between 0.5 µm and 20 µm, without any limitation. The above-mentioned settings ensure that the length of the expansion section remains within this reasonable range.This prevents the effective reduction of plasma-to-environment exchange during passivation layer deposition from being compromised by an excessively short extension section. It also prevents the etching process from being unduly hampered by an excessively long extension section resulting in an insufficiently large opening in isolation zone 15. Furthermore, it avoids the risk of the extension section breaking due to its excessive length.

[0098] As in Fig. As shown in Figure 14, only the first doped conductive layers 161 have the second extension sections 310, and only the second extension sections 310 of the first doped conductive layers 161 have second sunken structures 177.

[0099] If the first doped conductive layers 161, the first tunnel layers 200 and the silicon substrate 1 of the first zones 13 are all provided with extension sections, as for example in the Fig. 15 and Fig. In the structure shown in Figure 12, the first doped conductive layers 161 and the first tunnel layers 200 are arranged with the second extension sections 310, and the first zones 13 are arranged with the first extension sections 140, and at this time the second extension sections 310 and the first extension sections 140 each have second sunken structures 177.

[0100] It should be noted that the arrangement of the film layer structures with the extension sections and the shapes of the extension sections represent an example of embodiments of the present disclosure and do not limit the present disclosure. In some other embodiments, other structural shapes can also be designed. For example, in some embodiments, when the silicon substrate 1 is etched with acid or alkali, it is etched rapidly. This reduces the etch rate of the areas of the silicon substrate 1 near the first tunnel layers 200 and near the first doped conductor layers 161. This causes the side walls of the silicon substrate 1 in the first zones 13 to taper and form the first extension sections 140. The areas of the first tunnel layers 200 and the first doped conductor layers 161 near the insulation zone 15 project beyond the first extension sections 140.The protruding areas of the first tunnel layers 200 are subsequently removed in a cleaning process. Only the protruding areas of the first doped conductor layers 161 remain and form the second extension sections 310. Only the second extension sections 310 exhibit the second sunken structures 177. As in . Fig. 16 and Fig. As shown in Figure 17, this is not limiting. It is evident that in this embodiment, the extension sections formed by extending the edges of the first doped conductive layers 161, the first tunnel layers 200, and the silicon substrate 1 of the first zones 13 towards the center of the opening 15 of the isolation zone comprise the first extension sections 140 and the second extension sections 310, as shown in Fig. 16 and Fig. 17 shown.

[0101] During implementation, the second recessed structures 177 are created by laser etching when the film layers are removed by laser during the preparation of the back-contacted solar cell. For example, when removing the passivation layer or a BSG (Back Surface Field Silicon Wafer), the laser etches the second recessed structures 177 in the regions of the first doped conductive layers 161 and / or the first tunnel layers 200 located on the extension sections.

[0102] Optionally, the diameter of the second recessed structure is 177 0.1 µm to 5 µm, for example 0.2 µm, 0.5 µm, 1 µm, 2 µm, 3 µm or 4 µm, with no restriction.

[0103] In some embodiments, the second recessed structure 177 can be a blind hole or a punched hole. The nature of the second recessed structure 177 can be either a blind hole or a punched hole and is determined, in particular, by the duration and power of the laser irradiation at the location of the second recessed structure 177. For example, at constant power, one second recessed structure 177 is exposed to a shorter laser irradiation duration, so that this second recess 177 is a blind hole, and another second recess 177 is exposed to a longer laser irradiation duration, so that this other second recess 177 is a punched hole. However, these possibilities are not limiting.

[0104] During the subsequent deposition of the passivation layers, these second embedded structures 177 can further reduce the exchange between the plasma in the isolation zones 15 and the environment, thus further improving the passivation and anti-damping effects.

[0105] The back-contacted solar cell of the present disclosure comprises the silicon substrate 1, the first tunnel layers 200, and the first doped conductive layers 161. The silicon substrate 1 has an illuminated side 11 and an unilluminated side 12, which are opposite each other. The unilluminated side 12 is provided with several first zones 13 and several second zones 14, the first zone and the second zone being arranged sequentially and alternately in the first direction. Each adjacent first zone 13 and second zone 14 are separated from each other by the isolation zone 15. The first doped conductive layers 161 are located on the silicon substrate 1 of the first zones 13. The first tunnel layers 200 are located between the first doped conductive layers 161 and the silicon substrate 1 of the first zones 13. The edges of the first doped conductive layers 161The tunnel layers 200 and the silicon substrate 1 of the first zones 13 all extend towards the center of the opening 15 of the isolation zone to form the extension sections, or only the first doped conductive layers 161 extend towards the center of the opening 15 of the isolation zone to form the extension sections, and the extension section has the second recessed structure 177. The arrangement of the extension sections reduces the opening 15 of the isolation zone. This reduces the exchange between plasma and environment during the subsequent deposition of the passivation layers and achieves a partial distribution of the hydrogen content of the passivation layers, so that the mobile oxygen content of the passivation layers is lower in the isolation zone 15 and higher in the remaining zones.This effectively improves the passivation and damping effects. Furthermore, the formation of the second recessed structures 177 in the extension sections facilitates the identification and alignment of subsequent processes, while simultaneously ensuring the passivation of a polysilicon film and guaranteeing the efficiency of the solar cell.

[0106] In some embodiments of the present disclosure, the rear contacts of the solar cell further comprise second tunnel layers 400 and second doped conductive layers 162; and the second doped conductive layers 162 are located on the silicon substrate 1 of the second zones 14, and the second tunnel layers 400 are located between the second doped conductive layers 162 and the silicon substrate 1 of the second zones 14.

[0107] In the implementation, the first doped conductive layer 161 can be either a p-doped or an n-doped layer, and the second doped conductive layer 162 can be the other of the p-doped layers, namely an n-doped layer. For example, in some embodiments, the first doped conductive layer 161 can be a p-doped layer, the second doped conductive layer 162 an n-doped layer, and both the first tunnel layer 200 and the second tunnel layer 400 can have one or combinations of several of the following properties: a tunnel oxide layer (e.g., a tunnel silicon oxide layer), an intrinsic silicon carbide layer, and an intrinsic amorphous silicon layer, the latter not being particularly limiting.The first tunnel layer 200 and / or the second tunnel layer 400 contain at least one of the following layers: an amorphous silicon layer, a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbon oxynitride layer, a titanium oxide layer, a hafnium oxide layer and an aluminum oxide layer.

[0108] In some embodiments of the present disclosure, the back-contacted solar cell further provides passivation layers 18, first electrodes 700 and second electrodes 800, wherein the passivation layers 18 cover the first doped conductive layers 161, the second doped conductive layers 162 and the insulating regions 15, and the first electrodes 700 penetrate the passivation layers 18 to connect with the first doped conductive layers 161, and the second electrodes 800 penetrate the passivation layers 18 to connect with the second doped conductive layers 162, wherein the first electrodes 700 and the second electrodes 800 are all metal electrodes.

[0109] The passivation layer 18 is a passive antireflection thin film, and the passive antireflection thin film is used to improve the efficiency of the photoelectric conversion and the stability of the solar cell, reduce surface damage and oxidation reactions of the solar cell, and extend the lifetime of the solar cell.

[0110] Optionally, the passivation layer 18 may contain at least one of the following layers: an amorphous silicon layer, a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbon oxynitride layer, a titanium oxide layer, a hafnium oxide layer or an aluminum oxide layer, without any restriction.

[0111] Optionally, the unilluminated side 12 of the silicon substrate 1 can be a polished or a structured surface. The structured surface can have a relatively high roughness, for example, a textured surface, which reduces light reflection, increases light absorption, alters the absorption of light, changes the angle of incidence and propagation path of the light, forms a light trap, and increases the density of charge carriers generated by photons, thereby improving the photoelectric conversion rate of the cell. Example 7

[0112] In some optional embodiments, the present disclosure further provides a photovoltaic module, including the back-contacted solar cell described above.

[0113] It can be assumed that the photovoltaic module may still comprise a metal frame, a backplate, photovoltaic glass, and an adhesive film (not shown), with the adhesive film being applied between the illuminated side 11 of the back-contacted solar cell and the photovoltaic glass, as well as between the unilluminated side 12 of the back-contacted solar cell and the photovoltaic glass. The backplate is applied between adjacent back-contacted solar cells. A transparent adhesive film with good light transmission and aging resistance serves as the filler material, for example, an EVA (ethylene-vinyl acetate copolymer) or a POE (polyolefin elastomer) adhesive film. The choice of material depends on the specific requirements and is not limited here. The photovoltaic glass covers the adhesive film on the illuminated side 11 of the back-contacted solar cell.Highly transparent glass can be used, exhibiting high light transmittance and transparency as well as excellent physical, mechanical, and optical properties. For example, the light transmittance of the highly transparent glass can exceed 92%. It provides optimal protection for the back-contacted solar cell without impairing its efficiency. The adhesive film bonds the photovoltaic glass to the back-contacted solar cell, sealing, insulating, and protecting it from water and moisture.

[0114] The backplate can be attached to the adhesive film on the unilluminated side 12. In back-contacted solar cells, the backplate serves to protect and support the solar cell and provides reliable insulation, water resistance, and aging resistance. Several options are available for the backplate. Generally, these can include tempered glass, organic glass, an aluminum alloy TPT (Tedlar / PET / Tedlar) composite adhesive film, and similar materials. The selection can be customized depending on specific conditions, and the information provided herein is not exhaustive.

[0115] A unit consisting of the backplate, the back-contacted solar cell, the adhesive film, and the photovoltaic glass can be mounted on the metal frame. The metal frame serves as the main external support structure for the entire photovoltaic module, ensuring stable support and installation. For example, the photovoltaic module can be installed in a desired position using the metal frame.

[0116] It is clear to those skilled in the art in the field to which the present disclosure belongs that, in order to simplify and brevity the description of the structure and operating principle of the photovoltaic module described above, reference can be made to the corresponding structures and operating principles in the preceding embodiment 1, and therefore the details are not described again here.

[0117] A back-contacted solar cell according to the present disclosure comprises a silicon substrate 1, first tunnel layers 200, and first doped conductive layers 161. The silicon substrate 1 has an illuminated side 11 and an unilluminated side 12 facing each other; and the unilluminated side 12 is provided with several first zones 13 and several second zones 14, the first zone and the second zone being arranged sequentially and alternately in a first direction, each adjacent first zone 13 and second zone 14 being separated from each other by the isolation zone 15, and the first doped conductive layers 161 being located on the silicon substrate 1 of the first zones 13. The first tunnel layers 200 are located between the first doped conductive layers 161 and the silicon substrate 1 of the first zones 13.The edges of the first doped conductive layers 161, the first tunnel layers 200, and the silicon substrate 1 of the first zones 13 all extend towards the center of the opening 15 of the isolation zone to form the expansion sections, or only the first doped conductive layers 161 extend towards the center of the opening of the isolation zone 15 to form expansion sections, the expansion sections having second recessed structures 177. The arrangement of the expansion sections reduces the size of the opening 15 of the isolation zone.This reduces the exchange between plasma and environment during subsequent deposition and achieves a partial distribution of the hydrogen content of the passivation layers, resulting in a lower mobile oxygen content in the insulation zone 15 and a higher mobile oxygen content in the remaining zones. This effectively improves the passivation and damping effects. Furthermore, the formation of the second recessed structures 177 in the extension sections facilitates the identification and alignment of subsequent processes, while simultaneously ensuring the passivation of a polysilicon film and maintaining the efficiency of the solar cell. Example 8

[0118] In some optional embodiments, the present disclosure further provides a photovoltaic system, including the photovoltaic module described above.

[0119] During implementation, the photovoltaic system can be used, for example, in photovoltaic power plants, such as ground-mounted, rooftop, or hydroelectric power plants. It can also be used in devices and systems that utilize solar energy for electricity generation, such as solar power supplies for end users, solar streetlights, solar vehicles, solar buildings, etc. Of course, the application scenarios for the photovoltaic system are not limited to these. It can be used in all areas where electricity generation using solar energy is required. Let's take a photovoltaic power generation system grid as an example: The photovoltaic system can include a photovoltaic array, a combination box, and an inverter. The photovoltaic array can be a combination of several photovoltaic modules; for example, the multiple photovoltaic modules can form several photovoltaic arrays.The photovoltaic array is connected to the combination box. The combination box can combine the electricity generated by the photovoltaic array, and the combined electricity flows through the inverter to be converted into alternating current required for the power grid, and is then connected to a power grid to provide solar power.

[0120] It is clear to those skilled in the art in the field to which the present disclosure belongs that, for the sake of simplicity and brevity of the description regarding the structure and operating principle of the photovoltaic module described above, reference can be made to the corresponding structures and operating principles in the preceding embodiments 1 and 2, and therefore the details are not described again here.

[0121] A back-contacted solar cell according to the present disclosure comprises a silicon substrate 1, first tunnel layers 200, and first doped conductive layers 161, wherein the silicon substrate 1 has an illuminated side 11 and an unilluminated side 12 facing each other. The unilluminated side 12 is provided with several first zones 13 and several second zones 14, wherein the first zone and the second zone are arranged sequentially and alternately in a first direction, each adjacent first zone 13 and second zone 14 being separated from each other by the isolation zone 15, and the first doped conductive layers 161 are located on the silicon substrate 1 of the first zones 13, and the first tunnel layers 200 are located between the first doped conductive layers 161 and the silicon substrate 1 of the first zones 13.The edges of the first doped conductive layers 161, the first tunnel layers 200 and the silicon substrate 1 of the first zones 13 all extend towards the center of the opening 15 of the isolation zone to form the extension sections, or only the first doped conductive layers 161 extend towards the center of the opening of the isolation zone 15 to form extension sections, the extension sections having second sunken structures 177.The arrangement of the extension sections reduces the opening 15 of the isolation zone, thereby reducing the exchange between plasma and the environment during subsequent deposition. This allows for a partial distribution of the hydrogen content of the passivation layers, resulting in a lower mobile oxygen content in the isolation areas 15 and a higher mobile oxygen content in the remaining zones. This effectively improves the passivation and damping effects. Furthermore, the formation of the second recessed structures 177 in the extension sections facilitates the identification and alignment of subsequent processes, while simultaneously ensuring the passivation of a polysilicon film and maintaining the efficiency of the solar cell.

[0122] In relation to Fig. 18 and Fig.19. A photovoltaic system 1000 according to the embodiments of the present disclosure may comprise: a cell module 1001 according to the embodiments of the present disclosure, which may comprise a plurality of back-contacted solar cells 100 according to the embodiments of the present disclosure.

[0123] In the embodiments described in this disclosure, the numerous back-contacted solar cells 100 in the cell module 1001 can be connected in series to form multiple cell strings. The cell strings can then be connected in series, parallel, or in a combined series-parallel configuration to achieve a common current output. For example, cells can be connected by solder strips and cell strings by a busbar. In some embodiments, the cell strings can form cell arrays, which are then joined together by a front panel, a front adhesive film, a rear adhesive film, and a back panel to form the cell module 1001.

[0124] In some optional embodiments, a back-contacted solar cell comprises first zones and second zones arranged on the unilluminated side of a silicon substrate, the first and second zones being arranged sequentially and alternately. The first zone comprises first-doped conductive layers, and the second zone comprises second-doped conductive layers. The first and second-doped conductive layers have opposite doping types. The alternating orientation of the first and second zones is a first direction. The first and second zones all extend in a third direction, with the first direction intersecting the third direction, and the back-contacted solar cell comprises multiple first and multiple second-doped conductive layers. The first-doped conductive layers cover at least a portion of the first zones.Each first zone is provided with the first doped conductive layer, and at least some of the first doped conductive layers have first recessed structures. The second doped conductive layers cover at least part of the second zones, and every second zone is provided with the second doped conductive layer. At least some of the second doped conductive layers have leakage-prone contacts that extend to the first doped conductive layers, and these leakage-prone contacts extend into the first recessed structures, and the leakage-prone contacts are in leakage contact with the first doped conductive layers, at least in the first recessed structures.

[0125] In particular, the back-contacted solar cell 100 can be used in the embodiments of the present disclosure as shown in Fig. 20 and Fig.Figure 21 shows a silicon substrate 1, comprising several first doped conductive layers 161 and several second doped conductive layers 162.

[0126] The silicon substrate 1 has an illuminated side 11 and an unilluminated side 12, which are opposite each other. The unilluminated side 12 comprises first zones 13 and second zones 14, which are arranged alternately in the first direction. The first zones 13 and the second zones 14 all extend in the third direction, and the third direction intersects the first direction.

[0127] As in Fig.As shown in Figure 20, the first zones 13 and the second zones 14 can be arranged alternately in a direction transverse to the silicon substrate 1 and extend longitudinally. The first direction can run transversely to the back-contacted solar cell 100, and the third direction runs in the transverse direction of the back-contacted solar cell 100, with the two directions being perpendicular to each other. Of course, in other embodiments, the first and third directions can also have other directions, for example, diagonal directions of the silicon substrate 1. This is not limited to specific directions here. The first doped conductive layers 161 are arranged on the first zones 13 and cover at least a portion of the first zones 13. Each first zone 13 is provided with the first doped conductive layer 161. The number of the first doped conductive layers 161 corresponds to the number of the first zones 13.On at least some of the first doped conductive layers 161, the first sunken structures 173 have formed.

[0128] The second doped conductive layers 162 are arranged on the second zones 14 and cover at least a portion of the second zones 14. Every second zone 14 is provided with the second doped conductive layer 162. The number of second doped conductive layers 162 corresponds to the number of second zones 14. At least some of the second doped conductive layers 162 are provided with leakage current-prone contacts 31 that extend to the first doped conductive layer 161. The leakage current-prone contacts 31 extend partially into the first recesses 173 and are in leakage current contact with the first doped conductive layer 161, at least in the first recesses 173.

[0129] It should be noted that a specific structural layer covers part or all of the surface. This can mean that one structural layer covers another, or that the structural layer is stacked directly on the surface or on a specific film layer, or that another film layer is positioned between the film layer and the surface or between the film layers. The covering serves only to limit the specific adjustment range of the film layer.

[0130] Furthermore, it should be noted that the term "leakage contact" here means that the leakage-prone contact 31 and the first doped conductive layer 161 are not insulated, but rather exhibit an electrical leakage current to form an electrical leakage point. The leakage-prone contact 31 and the first doped conductive layer 161 can be in direct contact, thus forming a leakage point. Tunneling can also be achieved through other dielectric layers to create a leakage contact function; for example, the leakage-prone contact 31 and the first doped conductive layer 161 can be directly coated with dielectric layers (e.g., tunnel oxide layers, etc.) exhibiting electrical conductivity.

[0131] In the back-contacted solar cell 100, the cell module 1001, and the photovoltaic system 1000 according to the embodiments of the present disclosure, the first recessed structures 173 are formed at least partially on the first doped conductive layers 161, and the second doped conductive layers 162 are provided with the leakage current-prone contacts 31, which extend onto the first doped conductive layers 161, and the leakage current-prone contacts 31 extend partially into the first recessed structures 173 and form a leakage current contact with the first doped conductive layers 161, at least in the first recessed structures 173. In this way, the leakage current-prone contacts 31 of the second doped conductive layers 162 can form a leakage contact with the first doped conductive layers 161 in the first recesses 173.This creates leakage current points in the first recessed structures 173, which reduce the blocking voltage when the back-contacted solar cell 100 is shaded. This improves the hotspot resistance of the back-contacted solar cell 100 and reduces the hotspot risk of the cell module 1001. At the same time, the arrangement of the first recessed structures 173 ensures the accuracy of the contact surface, increases the leakage contact area, further optimizes the hotspot resistance of the back-contacted solar cell 100, and guarantees the consistency of the hotspot resistance of the back-contacted solar cells 100 in the production process.

[0132] In particular, the silicon substrate 1 in the embodiments of the present disclosure can be an n-doped or a p-doped silicon substrate 1, without further restriction here. The first doped conductive layer 161 can be n-doped and the second doped conductive layer 162 p-doped, or the first doped conductive layer 161 is p-doped and the second doped conductive layer 162 is p-doped, without further restriction here, as long as the first doped conductive layer 161 and the second doped conductive layer 162 have opposite polarities.

[0133] In the embodiments described in this disclosure, at least one first recessed structure 173 can be formed on all first doped conductive layers 161, and all second doped conductive layers 162 are provided with at least one leakage current-prone contact 31. Alternatively, the first recesses 173 can be formed on all first doped conductive layers 161, and some of the second doped conductive layers 162 are provided with the leakage current-prone contacts 31; or the first recessed structures 173 can be formed on some of the first doped conductive layers 161, and some of the second doped conductive layers 162 are provided with the leakage current-prone contacts 31, which is not specifically restricted here as long as the efficiency of the back-contacted solar cell 100 is not significantly reduced by the leakage current contact area, e.g.The efficiency loss is kept within 0.3%.

[0134] In some embodiments, such as in Fig. As shown in Figure 21, a first tunnel layer 200 is arranged between the first doped conductive layer 161 and the silicon substrate 1 of the first zone 13. A second tunnel layer 400 is arranged between the second doped conductive layer 162 and the silicon substrate 1 in the second zone 14.

[0135] The passivation effect can be improved by arranging the first tunnel layer 200 and the second tunnel layer 400. Specifically, both the first tunnel layer 200 and the second tunnel layer 400 can consist of layer materials such as tunnel oxide layers, intrinsic amorphous silicon layers, etc.

[0136] In some embodiments, such as in Fig.As shown in Figure 21, a dielectric layer 60 is arranged in a region of the first recessed structure 173 that is covered by the leakage current-prone contact 31. The leakage current-prone contact 31 covers the dielectric layer 60, and the leakage current-prone contact 31 is in leakage current contact with the first doped conductive layer 161 in the first recessed structure 173 through the dielectric layer 60.

[0137] The arrangement of the dielectric layer 60 allows the leakage current-prone contact 31 to establish a leakage current contact with the first doped conductive layer 161, while simultaneously improving passivation. This leads to an increase in local thermal resistance and improved passivation. The dielectric layer 60 can be a conductive layer, for example, a tunnel oxide layer.

[0138] As in Fig.As shown in Figure 21, in some embodiments both the first doped conductive layer 161 and the second doped conductive layer 162 can be doped polysilicon layers, and both the first tunnel layer 200 and the second tunnel layer 400 are tunnel oxide layers.

[0139] As in Fig.As shown in Figure 21, in this case the entire unilluminated side 12 is additionally covered with the passivation layer 18. The passivation layer 18 forms the outermost layer of the unilluminated side 12 of the back-contacted solar cell 100. A first electrode 700 is located above the first doped conductive layer 161, and a second electrode 800 is located above the second doped conductive layer 162. The first electrode 700 can penetrate the passivation layer 18 and establish a conductive connection with the first doped conductive layer 161. Likewise, the second electrode 800 can penetrate the passivation layer 18 and establish a conductive connection with the second doped conductive layer 162. The first electrode 700 and the second electrode 800 can be applied by processes such as burn-through, slot filling, or electroplating.

[0140] It is evident that in such an embodiment, the leakage current-prone contact 31 of the second doped conductive layer 162 extends to the top surface of the first doped conductive layer 161, and the first electrode 700 must avoid this contact 31. Therefore, in one embodiment, the first electrode 700 can be arranged on one side of the leakage current-prone contact 31 without overlapping it in the thickness direction. The electrode 700 can be continuously bonded to the portion of the first doped conductive layer 161 that is not covered by the leakage current-prone contact 31 in the third direction using a bonding paste. Alternatively, a continuous electrode groove can be formed in the passivation layer 18 in the third direction, into which the first electrode 700 is applied by deposition or electroplating.Naturally, the first electrode 700 can also overlap at least partially with the leakage current-prone contact 31 in the thickness direction. In this case, interrupted spacer grooves are first formed in the passivation layer 18, i.e., electrode grooves are formed in areas without the leakage current-prone contact 31, and electrode grooves are not formed at the leakage current-prone contact 31. Then, an interrupted first electrode 700 is formed on the first doped conductive layer 161 by deposition and electroplating.

[0141] As in Fig.As shown in Figure 22, in some other embodiments the first doped conductive layer 161 can be a doped polysilicon layer, and the second doped conductive layer 162 can be a doped amorphous silicon layer or a doped microcrystalline silicon layer. In this case, the first tunnel layer 200 can be a tunnel oxide layer or an intrinsic amorphous silicon layer, and the second tunnel layer 400 can be a tunnel oxide layer or an intrinsic amorphous silicon layer.

[0142] As in Fig.As shown in Figure 22, in such an embodiment the entire unilluminated side 12 is additionally covered with a conductive thin film 120, for example a TCO thin film. The conductive thin film 120 can be the outermost layer of the unilluminated side 12 of the back-contacted solar cell 100. An insulating groove 1201 is formed in the conductive thin film 120 to separate the area of ​​the conductive thin film 120 at the location of the first zone from the area of ​​the conductive thin film 120 at the location of the second zone. The first electrode 700 can be arranged on the conductive thin film 120 in the first zone and the second electrode 800 on the conductive thin film 120 in the second zone. In this case, the first electrode 700 and the second electrode 800 are applied to the conductive thin film 120 by electroplating. As in Fig.As shown in Figure 21, in this embodiment the leakage current-prone contact 31, located outside the first recessed structure 173, is stacked in the thickness direction onto the first doped conductive layer 161, thus creating a stacked structure. The leakage current-prone contact 31 and the first doped conductive layer 161 extend in the thickness direction, and the insulating groove 1201 is formed at the position of the stacked structure.

[0143] In some embodiments, the leakage current-prone contact 31 can preferably completely cover all side wall surfaces and the bottom surface of the first recessed structure 173. Of course, the leakage current-prone contact 31 can also cover only a portion of the side wall surfaces and not the bottom surface, or only a portion of the side wall surfaces and the entire bottom surface, or only a portion of the side wall surfaces and a portion of the bottom surface, or all side wall surfaces but not the bottom surface, which is not specifically restricted here.

[0144] As in Fig.As shown in Figure 21, in some embodiments the first recessed structure 173 completely penetrates the first doped conductive layer 161 in the thickness direction of the first doped conductive layer 161 (i.e., in the thickness direction of the back-contacted solar cell 100), so that the silicon substrate 1 is exposed at the first recessed structure 173. The leakage current-prone contact 31 covers the silicon substrate 1 exposed at the first recessed structure 173 and covers at least a portion of the sidewall surfaces of the first recessed structure 173.

[0145] In this way, the first recessed structure 173 completely penetrates the first doped conductive layer 161. The first recessed structure 173 is a continuous groove that penetrates the first doped conductive layer 161. The silicon substrate 1 is exposed at the first recessed structure 173. The leakage current-prone contact 31 forms a leakage current contact with the first doped conductive layer 161 at the side wall of the first recessed structure 173 to improve the hotspot resistance. Simultaneously, the leakage current-prone contact 31 is in contact with the silicon substrate 1 at the bottom of the first recess 173. If the second doped conductive layer 162 serves as the emitter layer of the back-contacted solar cell 100, the emitter area of ​​the back-contacted solar cell 100 can be further increased by this arrangement, thus improving its efficiency.

[0146] In particular, in such an embodiment, the leakage current-prone contact 31 forms the leakage current contact only with the first doped conductive layer 161 on the side wall surface of the first recessed structure 173, and the part of the leakage current-prone contact 31 that is located at the bottom of the first recessed structure 173 serves as the emitter.

[0147] In some embodiments, the first recessed structure 173 penetrates according to Fig. 21 the first doped conductive layer 161 completely forms a groove 125 in the silicon substrate 1. The depth of the groove 125 in the silicon substrate 1 is 1 µm to 6 µm.

[0148] In this way, the configuration in which the first recessed structure 173 completely penetrates the first doped conductive layer 161 and forms the groove 125 in the silicon substrate 1 prevents the leakage current-prone contact 31 from forming a leakage current contact with the first doped conductive layer 161 at the bottom of the first recessed structure 173. Instead, a direct contact with the silicon substrate 1 is formed. If the second doped conductive layer 162 is an emitter, the emitter area can be increased, thereby improving the efficiency.

[0149] The penetration depth of the groove 125 on the silicon substrate 1 can be, for example, 1 µm, 1.5 µm, 2 µm, 2.5 µm, 3 µm, 3.5 µm, 4 µm, 4.5 µm, 5 µm, 5.5 µm, 6 µm or any numerical value between 1 µm and 6 µm.

[0150] In some embodiments, an inner expansion layer (not shown) is also formed in the part of the silicon substrate 1 corresponding to the first zone 13, the polarity of which 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 current-prone contact 31 is in leakage current contact with the surface of the inner expansion layer facing away from the silicon substrate 1.

[0151] In this way, the leakage current-prone contact 31 not only forms the leakage current contact with the first doped conductive layer 161 on the side wall of the first recessed structure 173, but also a leakage current contact with the inner expansion layer on the underside of the first recessed structure 173, so that the leakage current contact area can be increased and the hot spot resistance can be further improved.

[0152] In some embodiments, the first recessed structure 173 can also penetrate the inner expansion layer, and the leakage current-prone contact 31 is in leakage current contact with the side surface of the inner expansion layer facing the first recessed structure 173. As a result, the leakage current-prone contact 31 forms a leakage current contact not only with the first doped conductive layer 161, but also with the side surface of the inner expansion layer, thereby improving the resistance to hotspots.

[0153] In some embodiments, such as in Fig.As shown in Figure 23, the first recessed structure 173 does not completely penetrate the first doped conductive layer 161 in the thickness direction of the first doped conductive layer 161, and the leakage current-prone contact 31 covers at least part of the underside of the first recessed structure 173 as well as at least part of the side wall surface of the first recessed structure 173.

[0154] In this way, the first recessed structure 173 is a blind hole that does not completely penetrate the first doped conductive layer 161, and the leakage current-prone contact 31 can form the leakage current contact with the first doped conductive layer 161 on the bottom and side wall surface of the first recessed structure 173.

[0155] Furthermore, in some embodiments, the first recessed structure 173 does not completely penetrate the first doped conductive layer 161 in the thickness direction of the first doped conductive layer 161, and the depth of the first recessed structure 173 is 20 nm to 200 nm.

[0156] By appropriately controlling the penetration depth of the first recessed structure 173, the leakage contact area formed by the leakage current-prone contact 31 in the first recessed structure 173 can be kept within a reasonable range, thereby avoiding excessive efficiency loss.

[0157] In particular, in such an embodiment, the penetration depth of the first recessed structure 173 can be, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm or any numerical value between 20 nm and 200 nm, without any specific limitation.

[0158] As in Fig. 21 and Fig. As shown in Figure 24, the first doped conductive layer 161 has a first side surface 201 and a second side surface 202, which are opposite each other in the first direction. The first indented structure 173 does not penetrate either the first side surface 201 or the second side surface 202 (see Figure 24). Fig. 24). Both sides of the first recessed structure 173 are provided in the first direction with the first doped conductive layers 161.

[0159] In this way, the area of ​​the first sunken structure 173 can be kept within reasonable limits, thus avoiding excessive efficiency losses.

[0160] In particular, as in Fig. As shown in Figure 24, the first doped conductive layer 161 in this embodiment has a third side surface 203 and a fourth side surface 204, which are opposite each other in the third direction. The first recessed structure 173 is located in an intermediate region of the first doped conductive layer 161 and has only a notch facing away from the silicon substrate 1. That is, the first recessed structure 173 does not penetrate either the third side surface 203 or the fourth side surface 204. In some embodiments, however, the first recessed structure 173 can also penetrate at least one of the two side surfaces 203 or 204 in the third direction.

[0161] Furthermore, in some embodiments, one or more first sunken structures 173 may be present on a single first doped conductive layer 161. If a single first sunken structure 173 is present, it may not penetrate the first side face 201 and the second side face 202, nor the third side face 203 and the fourth side face 204, or it may penetrate the third side face 203 but not the fourth side face 204, or it may penetrate the third side face 203 and the fourth side face 204 simultaneously (i.e., the first sunken structure 173 extends continuously in the third direction and penetrates both ends of the first doped conductive layer 161 in the third direction).

[0162] In some embodiments, with a plurality of first recessed structures 173, not all of the first recessed structures 173 can penetrate the third side surface 203 and the fourth side surface 204. In some other embodiments, the first recessed structure 173 near the third side surface 203 can also pass through the third side surface 203, and the first recessed structure 173 near the fourth side surface 204 can also pass through the fourth side surface 204, which is not specifically limited herein.

[0163] As in Fig. 25 and Fig. As shown in Figure 26, the first recessed structure 173 can also penetrate at least one of the side surfaces 201 and 202 in some embodiments. For example, in one example, as shown in Fig. 25 and Fig.Figure 26 shows the first side face 201 and the second side face 202 of the first doped conductive layer 161 penetrating in the first direction. In another example, the first indented structure 173 can penetrate either only the first side face 201 or only the second side face 202 in the first direction; this is not explicitly restricted here.

[0164] In particular, as in Fig.As shown in Figure 25, in some embodiments the first recessed structures 173, which penetrate the first side surface 201 and the second side surface 202, can be formed on all first doped conductive layers 161, and two adjacent second doped conductive layers 162 are connected by the leakage current-prone contact 31, which is located in the first recessed structure 173, i.e. the leakage current-prone contact 31 traverses in the first direction the first doped conductive layer 161 in the first recessed structure 173 to connect the two adjacent second doped conductive layers 162 together.

[0165] In one such embodiment, the first recessed structure 173 can penetrate the first doped conductive layer 161 in the thickness direction, and in this case, the leakage current-prone contact 31 is in leakage contact with the first doped conductive layer 161 at the side wall surface of the first recessed structure 173. Of course, the first recessed structure 173 can also fail to penetrate the first doped conductive layer 161 in the thickness direction, and in this case, the leakage current-prone contact 31 is in leakage contact with the first doped conductive layer 161 at the side wall surface and / or the underside of the first recessed structure 173.

[0166] As in Fig.As shown in Figure 25, the leakage current-prone contact 31 can completely cover the underside of the first recess 173 if the first recessed structure 173 simultaneously penetrates the first side surface 201 and the second side surface 202. In this case, by forming the interrupted electrode grooves and carrying out the deposition and electroplating as described above, an interrupted electrode structure can be formed for the first electrode 700.

[0167] In some embodiments, the leakage current-prone contact 31 comprises according to Fig. 21 and Fig.23 a first section 311 located in the first recessed structure 173, and a second section 312 stacked on the surface of the first doped conductive layer 161 and facing away from the silicon substrate 1, wherein the first section 311 is in leakage current contact with the first doped conductive layer 161, and wherein a dielectric insulating layer 110 is arranged between the second section 312 and the first doped conductive layer 161.

[0168] In this way, only the first section 311 of the leakage current-prone contact 31, which is located in the first recessed structure 173, forms the leakage current contact with the first doped conductive layer 161, so that the leakage current contact area of ​​the back-contacted solar cell 100 can be controlled, thereby avoiding excessive efficiency loss due to an excessive leakage current contact area.

[0169] In particular, in such an embodiment, the second section 312 covers a different area than the first recessed structure 173, and the second section 312 is insulated and separated from the first doped conductive layer 161 by the dielectric insulating layer 110, and the leakage current-prone contact 31 forms the leakage current contact with the first doped conductive layer 161 exclusively via the first section 311. The dielectric insulating layer 110 can be a dielectric layer with an insulating function, such as a silicon oxide layer or a silicon nitride layer.

[0170] Of course, in some embodiments, the second section 312 can also form a leakage current contact with the surface of the first doped conductive layer 161, which faces away from the silicon substrate 1, provided that the efficiency of the rear-side contact solar cell is not significantly impaired. This is not a specific limitation here.

[0171] With reference to Fig. 21 and Fig. 23 In some embodiments, the leakage current-prone contact 31 extends along the side surface of the first doped conductive layer 161 to the surface of the first doped conductive layer 161 facing away from the silicon substrate 1 and into the first recessed structure 173. The leakage current-prone contact 31 also forms a leakage current contact with the first doped conductive layer 161 at its side surface.

[0172] In this way, the leakage current-prone contact 31 forms another leakage current contact with the first doped conductive layer 161 on its side surface, thereby improving the leakage current contact area and further improving the hotspot resistance.

[0173] Particularly in such an embodiment as in Fig. 21 and Fig. As shown in Figure 23, the leakage current-prone contact 31 of the second doped conductive layer 162, located on one side of the first side surface 201, can extend along the first side surface 201 of the first doped conductive layer 161 to the surface of the first doped conductive layer 161 facing away from the silicon substrate 1, and then extend further into the first recessed structure 173, with the leakage current-prone contact 31 forming a leakage current contact with the first side surface 201.

[0174] Of course, in some embodiments, the leakage current-prone contact 31 of the second doped conductive layer 162, which is located on one side of the second side surface 202, can extend along the second side surface 202 of the first doped conductive layer 161 to the surface of the first doped conductive layer 161, which faces away from the silicon substrate 1, and then extend further into the first recessed structure 173, wherein the leakage current-prone contact 31 also forms a leakage current contact with the second side surface 202, which is not specifically restricted here.

[0175] With reference to Fig.24 In some embodiments, in the first direction there is a first predetermined distance H1 between the first recessed structure 173 and the side surface (i.e. either the first side surface 201 or the second side surface 202, which is close to the first recessed structure 173) of the first doped conductive layer 161, wherein the size of the first predetermined distance H1 can be between 10 µm and 200 µm.

[0176] This prevents the first electrode 700 from being positioned off-center due to an excessive distance to the first side surface 201 or the second side surface 202. This excessive distance results from an excessive distance between the first recessed structure 173 and the first side surface 201 or the second side surface 202 of the first doped conductive layer 161. This improves the collection performance of the first electrode 700. Furthermore, it prevents the process difficulties from increasing significantly when the distance between the first recessed structure 173 and the first side surface 201 or the second side surface 202 of the first doped conductive layer 161 is too small.

[0177] In particular, as in Fig.As shown in Figure 24, in this embodiment the first recessed structure 173 cannot penetrate either the first side surface 201 or the second side surface 202. It can be arranged close to the first side surface 201. In this case, the second doped conductive layer 162 is provided with the leakage current-prone contact 31 near the first side surface 201. This leakage current-prone contact 31 extends into the first recessed structure 173. The first electrode 700 can be arranged between the first recessed structure 173 and the second side surface 202. It can form a continuous, uninterrupted structure. The first predetermined distance H1 lies within the aforementioned reasonable range, thus preventing an excessive reduction in the collector efficiency of the first electrode 700 due to an excessive distance to the first side surface 201.

[0178] In such an embodiment, the size of the first predetermined distance H1 can be, for example, 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 or any numerical value between 10 µm and 200 µm.

[0179] With reference to Fig. 24 The length L1 of the first recessed structure 173 in some embodiments in the first direction is 10 µm to 80 µm.

[0180] By appropriately controlling the length of the first recessed structure 173 in the primary direction, a significant reduction in collector efficiency can be avoided if the first electrode 700 cannot be positioned centrally due to an excessive width of the first recessed structure 173. In other words, by defining the length of the first recessed structure 173 in the primary direction within this appropriate range, the collector efficiency of the first electrode 700 can be improved.

[0181] In particular, in such an embodiment, the length L1 of the first recessed structure 173 in the first direction can be, for example, 10 µm, 20 µm, 30 µm, 40 µm, 50 µm, 60 µm, 70 µm, 80 µm or any numerical value between 10 µm and 80 µm.

[0182] With reference to Fig.24 The length L2 of the first recessed structure 173 in some embodiments in the third direction is 10 µm to 500 µm.

[0183] In this way, by setting the length of the first recessed structure 173 in the third direction within this appropriate range, it is avoided that excessive efficiency loss would be caused by an excessively large leakage current contact area in the first recessed structure 173.

[0184] In particular, in such an embodiment, the length L2 of the first recessed structure 173 in the third direction can be, for example, 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 any numerical value between 10 µm and 500 µm.

[0185] In some embodiments, the ratio of the length L2 of the first recessed structure 173 in the third direction to the length L1 of the first recessed structure 173 in the first direction is greater than or equal to 2.

[0186] In this way, to improve the collection performance, the leakage current contact area can be designed in such a way as to ensure hot spot resistance capability by specifying a larger length of the first recessed structure 173 in the third direction, even with a smaller groove width of the first recessed structure 173.

[0187] See Fig. 20, Fig. 24 and Fig. 25, in some embodiments, several first recessed structures 173 are located on a single first doped conductive layer 161, which are arranged at intervals in the third direction.

[0188] In this way, by arranging the multitude of isolated first recessed structures 173 on the first doped conductive layer 161, an excessive loss of efficiency caused by an excessively large leakage contact area on the single first doped conductive layer 161 can be avoided.

[0189] As in Fig. As shown in Figure 24, in some embodiments the first recessed structures 173 on the first doped conductive layer 161 can be arranged in a column in the third direction, which simplifies the process and improves efficiency.

[0190] Of course, in some embodiments, in order to avoid an excessive concentration of the first recessed structures 173, the first recessed structures 173 on the first doped conductive layer 161 can be arranged in at least two columns in the third direction.

[0191] Furthermore, in some embodiments, the distance H2 between two adjacent first sunken structures 173 in the third direction is in the range of 1 cm to 10 cm.

[0192] In this way, it can be avoided that the temperature rises sharply because the heat cannot be dissipated in time due to an excessive concentration of leakage stream points caused by an insufficient distance H2 between two adjacent first sunken structures 173.

[0193] In particular, in such an embodiment, the distance H2 between two adjacent first recessed structures 173 can be, for example, 1 cm, 1.5 cm, 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, 5 cm, 5.5 cm, 6 cm, 6.5 cm, 7 cm, 7.5 cm, 8 cm, 8.5 cm, 9 cm, 9.5 cm, 10 cm or any numerical value between 1 cm and 10 cm.

[0194] Furthermore, in such an embodiment, the distance H2 between two adjacent first recessed structures 173 in the third direction is preferably greater than or equal to 2 cm and less than 4 cm.

[0195] In this way, through research and demonstration by the inventors of the present disclosure, and by determining the spacing within this preferred region, excessive heat concentration can be maximally avoided when a larger number of first recessed structures 173 are provided. That is, the ratio between the heat point resistance and the excessive heat concentration can be balanced to achieve an optimal adaptation effect.

[0196] In particular, in such an embodiment, the distance H2 between two adjacent first recessed structures 173 may preferably be, for example, 2 cm, 2.2 cm, 2.4 cm, 2.6 cm, 2.8 cm, 3 cm, 3.1 cm, 3.2 cm, 3.3 cm, 3.4 cm, 3.5 cm, 3.6 cm, 3.7 cm, 3.9 cm or 3.95 cm.

[0197] In some embodiments, the regions in the first doped conductive layer 161 and the second doped conductive layer 162 that are not covered by the leakage-prone contact 31 are leakage-free regions, while all other regions in the first doped conductive layer 161 and the second doped conductive layer 162 are configured as leakage-prone regions. To reduce recombination in the leakage-free regions, the number of first recessed structures 173 per unit length is greater in the leakage-free regions than in the leakage-prone regions.

[0198] In some embodiments of the back-contacted solar cell 100, the distribution density of the recessed structures 173 is in the range of 0.01 to 1.5 pieces / cm². 2 . In this way, an excessively concentrated distribution of electrical leakage current points can be avoided by appropriately controlling the distribution density of the first sunken structures 173.

[0199] In such an embodiment, the distribution density of the first recessed structures 173 denotes the ratio of the sum of the number of first recessed structures 173 on the back-contacted solar cell 100 to the area of ​​the unilluminated side 12 of the back-contacted solar cell 100. The distribution density of the first recessed structures 173 can, for example, be 0.01 units / 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 / cm² 2 , 0.7 pieces / cm² 2 , 0.8 pieces / cm² 2 , 0.9 pieces / cm 2 , 1 piece / cm 2 , 1.1 pieces / cm² 2 , 1.2 pieces / cm 2 , 1.3 pieces / cm² 2 , 1.4 pieces / cm² 2 , 1.5 pieces / cm 2 , or any numerical value between 0.01 pieces / cm² 2 up to 1.5 pieces / cm² 2 be.

[0200] In some embodiments, the leakage current contact surface between the leakage current-prone contact 31 and the first doped conductive layer 161 is located in a single first recessed structure 173 in the range of 1.2 µm. 2 up to 1500 µm 2 .

[0201] In this way, by controlling the leakage current contact area within this appropriate range, it can be ensured that the efficiency loss is not too great while simultaneously improving the hotspot resistance.

[0202] In particular, in such an embodiment, the leakage current contact area between the leakage current-prone contact 31 and the first doped conductive layer 161 can be, for example, 1.2 µm. 2 , 2 µm 2 , 5 µm 2 , 10 µm 2 , 50 µm 2 , 100 µm 2 , 200 µm 2 , 300 µm 2 , 350 µm 2 , 400 µm 2 , 450 µm 2 , 480 µm 2 , 500 µm 2 , 600 µm 2 , 700 µm 2 , 800 µm 2 , 900 µm 2 , 1000 µm 2 , 1100 µm 2 , 1200 µm 2 , 1300 µm 2 , 1400 µm 2 , 1500 µm 2 , or any numerical value between 1.2 µm 2 and 1500 µm 2 be.

[0203] In some embodiments, the ratio of the total area on which all leakage current-prone contacts 31 are in contact with the first doped conductive layers 161 to the area of ​​the unilluminated side of the back-contacted solar cell 100 (i.e., the area of ​​the unilluminated side 12 of the silicon substrate 10) can be in the range of 4.5 × 10 -8 up to 1.5 × 10 -8 lay.

[0204] In this way, the ratio of the leakage current contact area to the unilluminated side 12 is adjusted within this appropriate range, thus preventing the efficiency of the back-contacted solar cell 100 from being seriously impaired by an excessively large leakage current contact area ratio. This ensures both high efficiency of the back-contacted solar cell 100 and low hotspot resistance.

[0205] In particular, 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 -8 or any other numerical value between 4.5 × 10 -8 and 1.5 × 10 -5 amount, although this is not explicitly limited here.

[0206] In some embodiments, the second zone is 14 according to Fig. 27 and Fig.29 is formed as a groove 123 in the silicon substrate 1. The first doped conductive layer 161 has a first projection 22 that extends to the top of the groove 123. The leakage current-prone contact 31 extends along a side wall surface of the groove 123, surrounds the first projection 22, covers the first doped conductive layer 161 and extends further into the first recessed structure 173.

[0207] In this way, the leakage current-prone contact 31 and the first projection 22 can also form a leakage current contact, thereby improving the hot spot resistance capability.

[0208] In particular, in such an embodiment, the first doped conductive layer 161 can be a p-doped layer, and the second doped conductive layer 162 can be an n-doped layer. The p-doped layer is provided with the first projection 22, and the leakage current-prone contact 31 can either form a leakage current contact only with the surface of the first projection 22 facing the groove 123, or form leakage current contacts with both this surface and simultaneously with a side wall surface of the first projection 22, without this being specifically restricted here.

[0209] In some embodiments according to Fig.In section 28, the second zone 14 is formed as a groove 123 in the silicon substrate 1. The first doped conductive layer 161 does not completely cover the first zone 13, so that an exposed area 124 is created in the first zone 13, which is not covered by the first doped conductive layer 161. This area is located between the first doped conductive layer 161 and the groove 123. The leakage current-prone contact 31 extends to and covers the exposed area 124.

[0210] In this way, if the second doped conductive layer 162 is the emitter of the back-contacted solar cell 100, the exposed area 124 can be increased, thereby improving the efficiency of the back-contacted solar cell 100. At the same time, the exposed area 124 ensures that the first doped conductive layer 161 is not exposed in the cross-section of the groove 123, thus reducing recombination.

[0211] Specifically, the first doped conductive layer 161 is an n-doped layer and the second doped conductive layer 162 is a p-doped layer.

[0212] Furthermore, in such an embodiment, the length L4 of the exposed area 124 in the first direction is in the range of 0.3 µm to 50 µm.

[0213] By defining the length of the exposed region 124 in the primary direction within this appropriate range, excessive recombination due to insufficient width can be avoided. Furthermore, the overall efficiency of the cell can be prevented from being negatively impacted by insufficient charge carrier collection performance resulting from an excessively large area of ​​the first doped conductive layer 161 due to excessive length.

[0214] In particular, in such an embodiment, the length L4 of the exposed area 124 can be, for example, 0.3 µm, 0.4 µm, 0.5 µm, 0.6 µm, 0.7 µm, 0.8 µm, 0.9 µm, 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 15 µm, 20 µm, 25 µm, 30 µm, 40 µm, 45 µm, 50 µm or any numerical value between 0.3 µm and 50 µm, without any specific restriction.

[0215] In some embodiments, the length L4 of the exposed area 124 in the first direction can preferably be 1 µm to 20 µm.

[0216] In some embodiments, the first recessed structure 173 penetrates according to Fig. 29 completely forms the first doped conductive layer 161 and creates a trench 125 in the silicon substrate 1. The first doped conductive layer 161, located on both sides of the trench 125, has a second projection 23 that extends to the top of the trench 125. The leakage current-prone contact 31 surrounds at least one second projection 23 and extends into the first recessed structure 173.

[0217] In this way, the leakage current-prone contact 31 and the projection 23 can also form a leakage current contact, thereby improving the hot spot resistance capability.

[0218] In particular, in such an embodiment, the first doped conductive layer 161 can be a p-doped layer, and the second doped conductive layer 162 can be an n-doped layer, and the p-doped layer is provided with the second projection 23, and the leakage current-prone contact 31 can either form a leakage current contact only with the surface of the second projection 23 facing the groove 123, or form leakage current contacts with both this surface and simultaneously with a side wall surface of the second projection 23, without this being specifically restricted here.

[0219] In some embodiments, the first recessed structure 173 penetrates according to Fig.30 the first doped conductive layer 161 completely forms a trench 125 in the silicon substrate 1. And between the first doped conductive layers 161, which are located on both sides of the trench 125, and an edge of the trench 125 there are second predetermined distances.

[0220] By arranging the second predetermined distance L5, the first doped conductive layer 161 in the cross-section of the trench 125 is not exposed, so that recombination can be reduced.

[0221] Specifically, the first doped conductive layer 161 is an n-doped layer and the second doped conductive layer 162 is a p-doped layer.

[0222] Furthermore, in such an embodiment, the size of the second predetermined distance L5 can be between 0.3 µm and 50 µm.

[0223] By specifying the size of the second predetermined distance L5 within this appropriate range, excessive recombination due to an insufficient second predetermined distance L5 can be avoided. Furthermore, this prevents the overall efficiency of the cell from being negatively impacted by insufficient charge carrier collection resulting from an excessively large area of ​​the first doped conductive layer 161 due to its excessive length.

[0224] In particular, in such an embodiment, the size of the second predetermined distance L5 can be, for example, 0.3 µm, 0.4 µm, 0.5 µm, 0.6 µm, 0.7 µm, 0.8 µm, 0.9 µm, 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 15 µm, 20 µm, 25 µm, 30 µm, 40 µm, 45 µm, 50 µm or any numerical value between 0.3 µm and 50 µm, whereby this specification is not specifically limiting.

[0225] In some embodiments according to Fig. 31, the second zone is a groove 123 formed in the silicon substrate 1. The first doped conductive layer 161 forms a step structure 24 at an edge of the side of the first doped conductive layer 161 facing the groove 123. The leakage current-prone contact 31 covers a side surface of the first doped conductive layer 161 and the step structure 24 and is in leakage current contact with the first doped conductive layer 161 at the step structure 24.

[0226] By arranging the stepped structure 24, the leakage current-prone contact 31 on the stepped structure 24 can form a leakage current contact with the first doped conductive layer 161, thereby improving the electrode of the leakage current contact and thus increasing the resistance to the formation of hotspots of the back-contacted solar cell 100.

[0227] In particular, as in Fig.As shown in Figure 31, the first doped conductive layer 161 has a step surface at the edge of its side facing the groove 123. The leakage current-prone contact 31 covers the step surface, connects the step surface to a contact surface on an outermost side face of the first doped conductive layer 161, which faces away from the silicon substrate 1, and is in leakage current contact with the first doped conductive layer 161 via the step surface and the contact surface.

[0228] The above description merely presents preferred embodiments of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, and the like made in accordance with the spirit and principles of the present disclosure fall within the scope of protection of the present disclosure. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] CN 202411017194.6

[0001] CH 202411151681.1

[0001] CH 202411231591.3

[0001]

Claims

[1] Back-contacted solar cell comprising first zones, second zones and isolation zones arranged on an unilluminated side of a silicon substrate, wherein the first zone and the second zone are arranged alternately and the isolation zone is located between the first zone and the second zone, wherein the first zone comprises a first doped conductive layer and the second zone comprises a second doped conductive layer, and the first doped conductive layer and the second doped conductive layer have opposite doping types;and wherein one side of the first zone facing the isolation zone has a recessed structure, wherein, if the silicon substrate is an n-doped silicon substrate, the first zone is a p-doped zone, the second zone is an n-doped zone, the side of the p-doped zone facing the isolation zone n1 has recessed structures, the side of the n-doped zone facing the isolation zone n2 has recessed structures, and wherein n1 > n2.; [2] Back-contacted solar cell according to claim 1, wherein the side of the first zone facing the insulation zone has discontinuous recessed structures; and / or a side of the second zone facing the insulation zone has recessed structures. [3] Back-contacted solar cell according to claim 2, wherein the side of the second zone facing the insulation zone has discontinuous recessed structures. [4] Back-contacted solar cell according to any one of claims 1 to 3, wherein the recessed structure comprises a first unit zone and a first recessed structure, the first unit zone is arranged around the first recessed structure, and the first recessed structure comprises a depression and a projection arranged in the depression; or wherein the first zone comprises an extension section extending and projecting towards the top of the insulation zone, the recessed structure comprises a second unit zone and a second recessed structure, the second unit zone is arranged around the second recessed structure, the extension zone comprises the second recessed structure, and the second recessed structure is a blind hole or a punched hole. [5] Back-contacted solar cell according to claim 4, wherein a height of the ledge is less than or equal to the depth of the depression; or the shape of the projection is pyramidal and / or frustoconical; or the silicon substrate has an illuminated side opposite the unilluminated side, the projection includes the silicon substrate and a passivation layer in a direction in which the illuminated side faces the unilluminated side, and a side wall of the recess includes the passivation layer. [6] Back-contacted solar cell according to claim 4, wherein a width of the base of the projection is 0.1 µm to 1.5 µm and the height of the projection is 0.01 µm to 10 µm; or the width of the opening of the depression is 0.1 µm to 2 µm and the depth of the depression is 0.01 µm to 10 µm. [7] Back-contacted solar cell according to claim 4, wherein the passivation layer of the back-contacted solar cell surrounds the extension section, and the second recessed structure penetrates the extension section and the passivation layer; or the width of the second recessed structure is 0.1 µm to 1.5 µm. [8] Back-contacted solar cell according to claim 2, wherein several recessed structures form an insulation transition zone, and the width of the insulation transition zone is 5 µm to 30 µm. [9] Back-contacted solar cell according to claim 8, wherein the width of the insulation transition zone is 10 µm to 15 µm. [10] Back-contacted solar cell according to claim 4, wherein a tunnel layer of the back-contacted solar cell comprises a first tunnel layer, the first tunnel layer being arranged between the first doped conductive layer and the silicon substrate of the first zone, and the first doped conductive layer, the first tunnel layer and an edge of the silicon substrate in the first zone all extending towards the center of an opening of the isolation zone to form the extension section, or only the first doped conductive layer extending towards the center of the opening of the isolation zone to form the extension section; and / or the tunnel layer of the back-contacted solar cell further comprises a second tunnel layer, the second tunnel layer being arranged between the second doped conductive layer and the silicon substrate of the second zone;or the passivation layer of the back-contacted solar cell covers the first doped conductive layer, the second doped conductive layer and the insulation zone, and the back-contacted solar cell further comprises a first electrode and a second electrode, wherein the first electrode penetrates the passivation layer to be connected to the first doped conductive layer, and the second electrode penetrates the passivation layer to be connected to the second doped conductive layer. [11] Back-contacted solar cell according to claim 10, wherein the diameter of the second recessed structure is 1.5 µm to 5 µm; or the length of the extension section is 0.1 µm to 40 µm. [12] Back-contacted solar cell according to claim 1, wherein the side of the first zone facing the isolation zone comprises a first target zone, the length of the first target zone in an extension direction of the isolation zone is greater than 50 µm, and the first target zone does not include the recessed structure; and the side of the second zone facing the isolation zone comprises a second target zone, the length of the second target zone in the extension direction of the isolation zone is greater than 50 µm, and the second target zone does not include the recessed structure. [13] Back-contacted solar cell comprising: a silicon substrate, wherein the silicon substrate has an illuminated side and an unilluminated side opposite the illuminated side, the unilluminated side comprising first zones and second zones, and the first zone and the second zone being arranged alternately in a first direction, the first zones and the second zones all extending in a third direction, and the third direction intersecting the first direction; several first doped conductive layers, wherein the first doped conductive layers are arranged on the first zones and cover at least a part of the first zones, each first zone is provided with the first doped conductive layer, and first recessed structures are formed on at least a part of the first doped conductive layers; and Several second doped conductive layers, wherein the second doped conductive layers are arranged on the second zones and cover at least a part of the second zones, each second zone is provided with the second doped conductive layer, at least a part of the second doped conductive layers is provided with leakage current-prone contacts extending to the first doped conductive layers, and a part of the leakage current-prone contacts extends into the first recessed structures, wherein the leakage current-prone contacts are in leakage current contact with the first doped conductive layers at least in the first recessed structures. [14] Back-contacted solar cell according to claim 13, wherein the leakage current-prone contact comprises a first part located in the first recessed structure and a second part resting on a surface of the first doped conductive layer facing away from the silicon substrate, wherein the first part is in leakage current contact with the first doped conductive layer, and a dielectric insulating layer is arranged between the second part and the first doped conductive layer; or the second part is in leakage current contact with the surface of the first doped conductive layer facing away from the silicon substrate; or wherein in the first direction the leakage current-prone contact extends along a side surface 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, wherein the leakage current-prone contact also forms a leakage current contact on the side surface of the first doped conductive layer; or wherein in the first direction there is a first predetermined distance between the first recessed structure and the side surface of the first doped conductive layer, wherein the first predetermined distance is 10 µm to 200 µm; or wherein in the first direction the length of the first sunken structure is 10 µm to 80 µm, and / or in the third direction the length of the first sunken structure is less than 10 µm to 500 µm. [15] Back-contacted solar cell according to claim 14, wherein the ratio of the length of the first recessed structure in the third direction to the length of the first recessed structure in the first direction is greater than or equal to 2. [16] Back-contacted solar cell according to claim 13, wherein the first doped conductive layer has a first side face and a second side face that are opposite each other in the first direction, and the first indented structure does not penetrate the first and second side faces, and on both sides of the first indented structure the first doped conductive layers are arranged in the first direction; or the first doped conductive layer has the first and second face opposite each other in the first direction, and the first indented structure penetrates at least one of the first and second face; or the first recessed structure completely penetrates the first doped conductive layer in one thickness direction of the first doped conductive layer, such that the silicon substrate is exposed at the first recessed structure, and the leakage current-prone contact covers the exposed silicon substrate as well as at least part of one side face 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 current-prone contact covers at least parts of a bottom of the first recessed structure and at least parts of the side surface of the first recessed structure; or the first indented structure completely penetrates the first doped conductive layer in the thickness direction of the first doped conductive layer and forms a trench in the silicon substrate, wherein the penetration depth of the trench in one thickness direction of the silicon substrate is 1 µm to 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 trench in the silicon substrate, wherein the first doped conductive layers have second projections on both sides of the trench extending to a top of the trench, and the leakage current-prone contact surrounds at least one of the second projections and extends into the first recessed structure; or the first sunken structure completely penetrates the first doped conductive layer in the thickness direction of the first doped conductive layer and forms a trench in the silicon substrate, with a second predetermined distance between the first doped conductive layers on both sides of the trench and an edge of the trench in the first direction. [17] Back-contacted solar cell according to claim 16, wherein an internal extension layer is formed in a part of the silicon substrate corresponding to the first zone, and a polarity of the internal extension layer corresponds to a doping type of the first doped conductive layer; the first indented structure does not penetrate the internal extension layer, and the leakage current-prone contact is in leakage current contact with a surface of the internal extension layer facing away from the silicon substrate; or the first recessed structure penetrates the internal extension layer, and the leakage current-prone contact is in leakage current contact with a side surface of the internal extension layer that is exposed at the first recessed structure. [18] Back-contacted solar cell according to claim 13, wherein the second zone is a groove formed in the silicon substrate, the first doped conductive layer comprises a first projection extending to a top surface of the groove, and the leakage current-prone contact extends along a side surface of the groove, surrounds the first projection, extends onto the first doped conductive layer and reaches into the first recessed structure; or the second zone is the groove formed in the silicon substrate, the first doped conductive layer does not completely cover the first zone, so that an exposed zone of the first zone exists between the first doped conductive layer and the groove, and the leakage current-prone contact extends into and covers the exposed zone; or a step structure is formed on an edge of the side of the first doped conductive layer facing the groove, and the leakage current-prone contact covers the step structure, and the leakage current-prone contact is in leakage current contact with the first doped conductive layer at the step structure. [19] Back-contacted solar cell according to claim 13, wherein a dielectric layer is arranged on an area in the first recessed structure which is covered by the leakage current-prone contact, and the leakage current-prone contact covers the dielectric layer, and the leakage current-prone contact is in leakage current contact with the first doped conductive layer in the first recessed structure above the dielectric layer. [20] Back-contacted solar cell according to claim 16, wherein the size of the second predetermined distance is 0.3 µm to 50 µm. [21] Back-contacted solar cell according to 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 penetration depth of the first recessed structure is 20 nm to 200 nm; or several first recessed structures are arranged on a single first doped conductive layer, spaced apart in the third direction. [22] Back-contacted solar cell according to 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 in at least two columns in the third direction. [23] Backside-contacted solar cell according to claim 13, wherein the distribution density of the first recessed structures in the backside-contacted solar cell is 0.01 pieces / cm² 2up to 1.5 pieces / cm² 2 is; or, in the case of a single first recessed structure, a leakage current contact area between the leakage current-prone contact and the first doped conductive layer is 1.2 µm. 2 up to 1500 µm 2 is; or in the back-contacted solar cell, a ratio of a total area on which all leakage current-prone contacts 31 are in contact with the first doped conductive layers 161 to the area of ​​the unilluminated side of the back-contacted solar cell in the range of 4.5 × 10 -8 up to 1.5 × 10 -5 lay. [24] Back-contacted solar cell according to claim 13, wherein zones in the first doped conductive layer and the second doped conductive layer that are not covered by the leakage current-prone contacts are leakage current-free zones, and zones in the first doped conductive layer and the second doped conductive layer that are not part of the leakage current-free zones are leakage current-prone zones; and within an equal unit length, the number of first recessed structures in the leakage current-free zones is greater than the number of first recessed structures in the leakage current-prone zones. [25] Photovoltaic module comprising the back-contacted solar cell according to any one of claims 1 to 24. [26] Photovoltaic system comprising the photovoltaic module according to claim 25.

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