Photovoltaic module, solar cell and preparation method thereof

Abstract

The invention discloses a photovoltaic module, a solar cell and a preparation method thereof, the solar cell comprises a substrate, the substrate is provided with a first surface and a second surface which are oppositely arranged, a first doped region is located on the first surface, in the first doped region, the doping concentration of an inactive element is 1E19-1E22, the doping concentration of an active element is 1E17-8E18, and the doping concentration of an active element is 1E17-8E18. And in the first doped region, in the direction from the first surface to the interior of the substrate, the doping concentration of the active element is firstly increased and then reduced, and the difference value between the maximum doping concentration of the active element and the doping concentration of the active element at the first surface is 1E18-7E18.

Description

Technical Field

[0001] This case is a divisional application of the invention patent application with the application date of May 24, 2024, application number 2024106605020, and invention name "Photovoltaic modules, solar cells and their preparation methods". Background Art

[0002] Improving photoelectric conversion efficiency and reducing production costs are the eternal goals of mass production of solar cells, aiming to reduce the cost per kilowatt-hour of photovoltaic power generation. At present, tunneling passivation structures are widely used in the field of solar cells, but the tunneling passivation structure requires a high concentration of doping elements to achieve effective passivation of the substrate and ensure cell efficiency. Moreover, the preparation of the tunneling passivation layer in the prior art is divided into a tunneling layer and a passivation layer, as well as subsequent doping preparation. Its multiple processes will inevitably lead to a long manufacturing time. At the same time, various steps need to match each other, the process window is narrow, the manufacturing difficulty is large, and the yield is difficult to control, especially it cannot match the new electrode preparation LECO process. Summary of the invention

[0003] In view of the problems existing in the prior art, the present application provides a solar cell, in which the doping elements in the first doping region are relatively low and the solar cell performance is good.

[0004] Specifically, this application involves the following aspects:

[0005] The present application provides a solar cell, including a substrate, wherein the substrate has a first surface and a second surface arranged opposite to each other, a first doping region is located on the first surface, in the first doping region, the doping concentration of the non-activated element is 1E19-1E22, the doping concentration of the activated element is 1E17-8E18, and in the first doping region, from the direction close to the first surface to the inside of the substrate, the doping concentration of the activated element first increases and then decreases, and the difference between the maximum doping concentration of the activated element and the doping concentration of the activated element at the first surface is 1E18-7E18. Compared with the prior art, the battery of the present application reduces the doping concentration of the activated element and the doping concentration of the non-activated element while maintaining the same electrical performance as the battery in the prior art. The lower the doping concentration, the smaller the recombination of the doping elements, the better the battery passivation effect, and the higher the corresponding battery open circuit voltage. Conventional cells in the prior art require a high doping concentration to match conventional screen printing in order to form a good metal semiconductor contact to collect the current generated by the substrate, while the present application adopts the LECO process, which can achieve a good contact between the first electrode and the first doping region on the first doping region with a lower doping concentration (metal semiconductor contact). Therefore, the solar cell of the present application matches the corresponding LECO process, which not only takes into account the low-recombination and low-surface doping concentration samples, but also can achieve good contact, thereby increasing the open circuit voltage of the battery and keeping the fill factor basically the same or even slightly improved.

[0006] In some embodiments, a first electrode is disposed on a surface of the first doped region away from the substrate, and a portion of the first electrode extends into the first doped region; the contact resistivity between the first electrode and the first doped region is 0.1 to 3 mΩ / cm 2 Since the LECO process is used in the preparation process of the battery, the contact resistivity between the first electrode and the first doping region is reduced compared with the prior art, thereby correspondingly reducing the doping concentration of the activated element and the doping concentration of the inactivated element in the first doping region while keeping the battery performance unchanged.

[0007] In some embodiments, the first surface corresponding to the first doped region has a first tower base-shaped texture structure; the first tower base-shaped texture structure includes a plurality of first tower bases; under a 20x microscope, within an area of ​​650 μm×650 μm, the number of orthographic projections of the first tower bases on the substrate that are quadrilaterals is 1-10; and / or the height of the first tower base is 0 to 0.3 μm, excluding 0; and / or the square resistance of the first doped region is 200 ohm-500 ohm, and within a depth range of 0.1-0.4 μm from the first surface, the first The doping region has a maximum doping concentration of the activation element; the junction depth of the first doping region is 1-1.5μm; if the first tower base is too high or the number of the first tower bases is too large, the roughness of the first surface will increase and the surface will be uneven, affecting the quality of the subsequent film layer stacked thereon; if the first tower base is too small, the density of the first tower base will increase, which will affect the quality of the subsequent film layer stacked thereon. At the same time, the appropriate tower base size correspondingly reduces the doping concentration of the activation element and the doping concentration of the non-activation element in the first doping region, thereby better matching the corresponding LECO process.

[0008] The depth difference between the maximum doping concentration of the activation element and the first surface and the depth difference between the junction depth and the first surface is 0.9-1.3 μm. The closer the location of the maximum doping concentration of the activation element is to the first surface, the closer the inactive element is to the first surface; the higher the doping concentration of the inactive element on the first surface, the easier it is to form a strong recombination area, and it is not easy to remove, resulting in a decrease in battery performance. In the present application, the location of the maximum doping concentration of the activation element can achieve the best passivation effect and contact effect.

[0009] In some embodiments, the first surface corresponding to the first doping region has a first pyramid-shaped texture structure, and the height of the first pyramid-shaped texture structure is 0.5-3μm; during the preparation of the battery, at this height, when preparing the first doping region, the diffusion process of the doping element has the least effect on the first pyramid-shaped texture structure. The first pyramid-shaped texture structure can not only take into account the reflectivity, but also bring a smaller tip area and a smaller high-recombination area of ​​the metal contact in the subsequent preparation of the contact process of the first electrode. At the same time, the appropriate pyramid size correspondingly reduces the doping concentration of the activation element and the doping concentration of the non-activation element in the first doping region, thereby better matching the corresponding LECO process. Within the depth range of 0.05-0.3μm from the first surface, the first doping region has a maximum doping concentration of the activation element; the junction depth of the first doping region is 0.8-1.2μm; the maximum doping concentration of the activation element plays a major role in the subsequent formation of the contact between the first electrode and the first doping region. Within the depth range of the location of the maximum doping concentration of the activation element, the first electrode and the first doping region achieve the best contact resistivity, which is conducive to the collection of photocurrent.

[0010] The depth difference between the maximum doping concentration of the activation element and the first surface and the depth difference between the junction depth and the first surface is 0.5-0.8 μm. The location of the maximum doping concentration of the activation element to the first surface and the location of the maximum doping concentration of the activation element to the substrate are the two most important areas involved in conduction, but the area from the location of the maximum doping concentration of the activation element to the first surface has the greatest impact on the recombination. Therefore, the ratio of the depth from the location of the maximum doping concentration of the activation element to the first surface to the entire junction depth is adjusted, so as to minimize the impact of surface recombination while ensuring contact.

[0011] In some embodiments, a first passivation layer and a first electrode are arranged on a side of the first doped region away from the second surface, the first passivation layer covers the first doped region, the first electrode includes a collector electrode extending along the second direction and arranged along the first direction, a partial area of ​​the collector electrode passes through the first passivation layer along the second direction to contact the first doped region, and the second direction intersects with the first direction.

[0012] In some embodiments, the first electrode further includes an interconnection portion, the interconnection portion is electrically connected to the collector electrode, and the interconnection portion is arranged along the second direction; the interconnection portion is located on the surface of the first passivation layer away from the first doping region, and the collector electrode includes a collector electrode portion, which is adjacent to the junction of the interconnection portion and the collector electrode along the second direction, and is located on the surface of the first passivation layer away from the first doping region or is located in the first passivation layer, and along the second direction, the size of the collector electrode portion is less than or equal to one third of the spacing between adjacent interconnections. The interconnection portion can prevent the first electrode with more intersections from damaging the contact between the first passivation layer and the first doping region below, causing more serious metal recombination.

[0013] In some embodiments, the battery further includes a second doping region, the second doping region is located on the first surface, the first doping region and the second doping region are arranged alternately, and the conductivity type of the second doping region is opposite to that of the first doping region; the first surface corresponding to the first doping region is a first tower base-shaped texture structure; the first surface corresponding to the second doping region has a second tower base-shaped texture structure; the second tower base-shaped texture structure includes a plurality of second tower bases;

[0014] The one-dimensional size of the second tower base is greater than or equal to the one-dimensional size of the first tower base;

[0015] The one-dimensional dimension of the second tower base is the dimension of the surface of one side of the second tower base away from the base;

[0016] The height of the second tower foundation is less than or equal to the height of the first tower foundation.

[0017] The film layers formed on the surfaces of the first tower base and the second tower base are different, so different requirements are placed on the morphology of the tower base. For the second doping region, the size of the second tower base needs to be as small as possible to ensure that the tunneling layer prepared on this morphology has higher quality. However, for the first doping region, the first tower base with certain undulations can increase the area of ​​the first doping region. At the same time, the morphology of the first tower base will affect the morphology of the second tower base. The first tower base is prepared first, and the second tower base corresponding to the second doping region is prepared on the basis of the first tower base.

[0018] In some embodiments, the battery further includes a second doping region, the second doping region is located on the first surface, the first doping region and the second doping region are arranged alternately; the second doping region has a conductivity type opposite to that of the first doping region; the first surface corresponding to the first doping region has a first pyramid-shaped texture structure, and the first surface corresponding to the second doping region has a second tower base-shaped texture structure; the second tower base-shaped texture structure includes a plurality of second tower bases;

[0019] The one-dimensional size of the second tower base is smaller than the one-dimensional size of the tower bottom of the first pyramid-shaped texture structure; the one-dimensional size of the second tower base is the size of the surface of the second tower base away from the base;

[0020] Under this matching, when preparing the first doping region, the diffusion process of the doping element has the least impact on the first pyramid-shaped texture structure. The first pyramid-shaped texture structure can take into account the reflectivity and bring a smaller tip area and a smaller high-recombination area of ​​the metal contact in the subsequent contact process of preparing the first electrode. At the same time, the appropriate pyramid size correspondingly reduces the doping concentration of the activated element and the doping concentration of the non-activated element in the first doping region, thereby better matching the corresponding LECO process. The second doping region adopts a second tower base structure. If the second tower base is too high, the roughness of the first surface corresponding to the second doping region becomes larger and the surface is uneven, which affects the quality of the subsequent film layer stacked thereon; if the second tower base is too small, the density of the second tower base will increase, which will affect the quality of the subsequent film layer stacked thereon.

[0021] The height of the second tower base is smaller than the height of the first pyramid-shaped texture structure, which is conducive to preparing a gap area that is easy to passivate.

[0022] In some embodiments, the battery further includes a second doping region and a first passivation layer, the second doping region is located on the first surface, the first doping region and the second doping region are arranged alternately; the second doping region has an opposite conductivity type to the first doping region; there is a gap region between the first doping region and the second doping region; the roughness of the first surface corresponding to the gap region is 0-1 μm; the first passivation layer covers the gap region. The passivation of the first surface of the gap region is achieved by the field passivation and hydrogen passivation of the first passivation layer (aluminum oxide and silicon nitride), but excessive roughness will result in poor film quality of the first passivation layer.

[0023] In some embodiments, the battery further includes a second doped region and a first passivation layer, the second doped region is located on the first surface, the first doped region and the second doped region are arranged alternately; the second doped region and the first doped region have a conductivity type opposite to that of the first doped region; there is a gap region between the first doped region and the second doped region; the first passivation layer covers the gap region;

[0024] The first surface corresponding to the first doping region is a first pyramid-shaped texture structure; the height difference between the first surface corresponding to the gap region and the first surface corresponding to the first doping region is 0.5-6μm; or the first surface corresponding to the first doping region is a first pyramid-shaped texture structure; the height difference between the first surface corresponding to the gap region and the first surface corresponding to the first doping region is 0.5-8μm. The passivation of the first surface of the spacing region is achieved through the field passivation and hydrogen passivation of the first passivation layer (aluminum oxide and silicon nitride). The first surface of the spacing region is lower than the first surface of the first doping region, thereby forming a pit in the gap region, which can increase the contact area between the first surface of the gap region and aluminum oxide and hydrogen, and the passivation surface is suspended, thereby strengthening the passivation of the first surface. When the pit is too deep, the aluminum oxide in the corresponding region will also be relatively thin, so the aluminum oxide passivation effect will be poor; when the pit is too shallow, during the battery preparation process, the original first doping region in the pit cannot be completely removed, and when preparing the second doping region, the residue will form a high-strength composite center with the new diffusion layer.

[0025] In some embodiments, the active element and the inactive element of the first doping region are both group III elements, the battery further comprises a second doping region, the second doping region is located on the first surface, the first doping region and the second doping region are arranged alternately; the second doping region comprises a tunneling layer and a second silicon-containing doping layer; one side surface of the tunneling layer is stacked on the first surface of the substrate, and the other side surface thereof is stacked with the second silicon-containing doping layer; the roughness of the first surface corresponding to the second doping region is less than or equal to 0.5 μm. Low roughness is conducive to the growth of a denser tunneling layer, so that the tunneling layer has a better chemical passivation and transmission effect.

[0026] In some embodiments, the battery also includes a second doped region, the second doped region is located on the second surface, the second surface has a third pyramid-shaped texture structure, the second doped region includes a tunneling layer and a second silicon-containing doped layer stacked in sequence, and the first doped region and the second doped region have opposite conductivity types. The first pyramid-shaped texture structure can take into account the reflectivity and bring a smaller tip area and a smaller high-recombination area of ​​the metal contact in the subsequent preparation of the contact of the first electrode. At the same time, the appropriate pyramid size correspondingly reduces the doping concentration of the activated element and the doping concentration of the non-activated element in the first doped region, so as to better match the corresponding LECO process. The second surface has a third pyramid-shaped texture structure. If the third tower base is too high, the roughness of the first surface corresponding to the second doped region becomes larger, and the surface is uneven, which affects the quality of the subsequent film layer stacked thereon; if the third tower base is too small, the density of the third tower base will increase, which will affect the quality of the subsequent film layer stacked thereon.

[0027] The present application also provides a method for preparing a solar cell, comprising the following steps:

[0028] Providing a substrate; the substrate having a first surface and a second surface disposed opposite to each other;

[0029] Doping elements enter the substrate from the first surface of the substrate to form a first doping region;

[0030] In the first doping region, the doping concentration of the inactive element is 1E19~1E22, and the doping concentration of the active element is 1E17~8E18. In the first doping region, in the direction from close to the first surface to the inside of the substrate, the doping concentration of the active element first increases and then decreases, and the difference between the maximum doping concentration of the active element and the doping concentration of the active element at the first surface is 1E18~7E18.

[0031] In some embodiments, after forming the first doping region, a first electrode is formed on the first doping region, and the first electrode at least partially extends into the first doping region.

[0032] In some embodiments, forming the first electrode comprises the following steps:

[0033] forming a first electrode precursor;

[0034] The first electrode precursor and the first doping region are processed by using the LECO process.

[0035] In some embodiments, when the first surface corresponding to the first doping region has a first pyramid-shaped texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the highest points of adjacent spires in the first pyramid-shaped texture structure; or

[0036] When the first surface corresponding to the first doping region has a first tower base-shaped texture structure, and the first tower base-shaped texture structure includes multiple first tower bases, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the geometric centers of adjacent first tower bases in the polishing surface.

[0037] In some embodiments, the prepared solar cell is the aforementioned solar cell.

[0038] The present application also provides a photovoltaic module, including the aforementioned solar cell, or a solar cell prepared by the aforementioned preparation method.

[0039] The solar cell provided in the present application adopts LECO technology in the preparation process of the battery, thereby reducing the contact resistivity between the first electrode and the first doping region compared with the prior art. On the basis of taking into account the battery performance, the doping concentration of the activated element and the doping concentration of the non-activated element in the first doping region are correspondingly reduced. As a result, the solar cell of the present application takes into account the low surface doping concentration of the low recombination in the first doping region, and can achieve good contact between the first doping region and the first electrode, thereby increasing the open circuit voltage of the battery and keeping the fill factor basically the same or even slightly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are used to better understand the present application and do not constitute an improper limitation on the present application.

[0041] Figure 1 This is a structural diagram of the solar cell provided in this application.

[0042] Figure 2 A partial structural diagram of the solar cell provided in this application.

[0043] Figure 3 A partial structural diagram of the solar cell provided in this application.

[0044] Description of Reference Numerals

[0045] 1-silicon substrate, 2-first doped region, 3-first electrode, 4-second silicon-containing doped layer, 5-tunneling layer, 6-second electrode, 7-passivation layer, 8-main electrode, 9-collecting electrode, 10-interconnection. DETAILED DESCRIPTION

[0046] The following is a description of the exemplary embodiments of the present application, including various details of the embodiments of the present application to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for clarity and conciseness, the description of well-known functions and structures is omitted in the following description.

[0047] The present application provides a solar cell, including a substrate, wherein the substrate has a first surface and a second surface arranged opposite to each other, a first doping region 2 is located on the first surface, within the first doping region 2, the doping concentration of the non-activated element is 1E19~1E22, the doping concentration of the activated element is 1E17~8E18, and within the first doping region 2, in a direction from close to the first surface to the inside of the substrate, the doping concentration of the activated element first increases and then decreases, and the difference between the maximum doping concentration of the activated element and the doping concentration of the activated element at the first surface is 1E18~7E18. The lower the doping concentration of the activated element and the doping concentration of the non-activated element, the smaller the recombination of the doped elements, the better the passivation effect of the battery, and the higher the corresponding battery open circuit voltage. Conventional batteries require high doping concentrations to match conventional screen printing to form good metal semiconductor contacts to collect the current generated by the substrate. The present application adopts the LECO process, which can achieve better contact between the first electrode and the first doping region (metal semiconductor contact) on a substrate with a lower doping concentration. Therefore, the solar cell of the present application matches the corresponding LECO process, which not only takes into account the low-recombination low-surface doping concentration samples, but also can achieve good contact, thereby increasing the battery open circuit voltage and keeping the fill factor basically the same or even slightly improved.

[0048] In this context, the first surface of the substrate is a backlight surface, and the second surface is a light-facing surface.

[0049] The first doping region 2 is located in the substrate and is a region close to the first surface (including the first surface), that is, the first doping region 2 is a region extending from the first surface to a certain depth into the substrate.

[0050] In some embodiments, in the first doping region 2 , the doping concentration of the inactive element may be 5E19-5E21.

[0051] In some embodiments, in the first doping region 2 , the doping concentration of the inactive element may be 5E19-1E21.

[0052] In some embodiments, in the first doping region 2 , the doping concentration of the activation element is 1E17-7E18.

[0053] In some embodiments, in the first doping region 2 , the doping concentration of the activation element is 1E17-5E18.

[0054] In some embodiments, in the first doping region 2 , the doping concentration of the activation element is 1E17-3E18.

[0055] In some embodiments, the difference between the maximum doping concentration of the activation element and the doping concentration of the activation element at the first surface is 1E18-3E18.

[0056] In some embodiments, the difference between the maximum doping concentration of the activation element and the doping concentration of the activation element at the first surface is 1E18-5E18.

[0057] Specifically, in the first doping region 2, the doping concentration of the inactive element may be 1E19, 2E19, 3E19, 4E19, 5E19, 6E19, 7E19, 8E19, 9E19, 1E20, 2E20, 3E20, 4E20, 5E20, 6E20, 7E20, 8E20, 9E20, 1E21, 2E21, 3E21, 4E21, 5E21, 6E21, 7E21, 8E21, 9E21 or 1E22.

[0058] Specifically, in the first doping region 2, the doping concentration of the activation element is 1E17, 2E17, 3E17, 4E17, 5E17, 6E17, 7E17, 8E17, 9E17, 1E18, 2E18, 3E18, 4E18, 5E18, 6E18, 7E18 or 8E18.

[0059] Specifically, in the first doping region 2 , the difference between the maximum doping concentration of the activation element and the doping concentration of the activation element at the first surface may be 1E18, 2E18, 3E18, 4E18, 5E18, 6E18 or 7E18.

[0060] Those skilled in the art can understand that the doping concentration of the doping element / activating element of the inactive element in the first doping region 2 can refer to the concentration of the doping element / activating element of the inactive element at any site on the surface of the first doping region 2 or in the first doping region 2, and of course, it can also be the average value of the doping element / activating element of the inactive element at multiple sites or the average value of the doping concentration of the doping element / activating element of the inactive element in the first doping region 2. Those skilled in the art can select the above-mentioned arbitrary sites for detection based on the actual situation based on the detection conditions and the instruments used, or calculate the average value of multiple sites after detecting multiple sites as the concentration of the doping element / activating element of the inactive element. In a specific embodiment, the concentration of the doping element / activating element of the inactive element refers to the average value detected on the thickness of the doping element / activating element of the inactive element, for example, the concentration of the doping element / activating element of the inactive element of the first doping region 2 is detected in a thickness direction using the SIMS method, and the average value in this thickness direction is calculated.

[0061] Herein, the doping concentration of the inactive element in the first doping region refers to the concentration value detected at any random site in the first doping region, and the doping concentration of the inactive element of 1E19 to 1E22 means that any detected concentration is within the range of 1E19 to 1E22.

[0062] Herein, the doping concentration of the activation element in the first doping region refers to the concentration value detected at any random site in the first doping region, and the doping concentration of the activation element 1E17~8E18 means that any detected concentration is in the range of 1E17~8E18.

[0063] In this article, the activated elements are generally tested by the ECV differential capacitance voltage method. The doping elements of the non-activated elements are tested by the ECV differential capacitance voltage method and the SIMS secondary ion mass spectrometry method. The ECV differential capacitance voltage method can measure the concentration of the doping elements involved in conduction. Compared with the doping element composition test of the SEMS secondary ion mass spectrometry test, the SIMS secondary ion mass spectrometry test is to test the total concentration of the element as A through SIMS when the doping element is known to be phosphorus or boron. The ECV differential capacitance voltage method can test the concentration of the doping element involved in conduction as B (that is, the doping concentration of the activated element), and the unactivated impurity concentration C is AB.

[0064] In this article, the active element is the doping element in the active state, and the inactive element is the doping element in the inactive state. The doping element itself has two functions. One is to participate in conduction (the role of the active element), and the other is the role of the recombination electrons or holes of the doping element itself (the role of the inactive element). The inactive element is a recombination center, that is, it captures carriers and hinders the movement of carriers. Therefore, the greater the doping concentration of the inactive element, the more carriers are captured, and the greater the battery performance degradation, which is mainly reflected in the open voltage. That is, as the concentration of the inactive doping element increases, the open circuit voltage of the battery will continue to decrease. Therefore, while meeting its conductivity, the smaller the doping concentration of the active element and the inactive element, the better the battery passivation effect, and the corresponding battery open circuit voltage is higher.

[0065] like Figure 2 A first electrode 3 is disposed on a surface of the first doping region 2 away from the substrate, and a portion of the first electrode 3 extends into the first doping region 2 .

[0066] The contact resistance between the first electrode 3 and the first doping region 2 is 0.1-5 mΩ / cm 2 In some embodiments, the contact resistivity is 0.1 to 3 mΩ / cm 2 In some embodiments, the contact resistivity is 0.1 to 1.5 mΩ / cm 2 .

[0067] Specifically, the contact resistivity between the first electrode 3 and the first doping region 2 may be 0.1 mΩ / cm 2 , 0.2mΩ / cm 2 , 0.3mΩ / cm 2 , 0.4mΩ / cm 2、0.5mΩ / cm 2 、1mΩ / cm 2 、1.1mΩ / cm 2 、1.2mΩ / cm 2 、.3mΩ / cm 2 、1.4mΩ / cm 2 、1.5mΩ / cm 2 、1.6mΩ / cm 2 、1.7mΩ / cm 2 、1.8mΩ / cm 2 、1.9mΩ / cm 2 、2mΩ / cm 2 、2.1mΩ / cm 2 、2.2mΩ / cm 2 、2.3mΩ / cm 2 、2.4mΩ / cm 2 、2.5mΩ / cm 2 、2.6mΩ / cm 2 、2.7mΩ / cm 2 、2.8mΩ / cm 2 、2.9mΩ / cm 2 、3mΩ / cm 2 、3.1mΩ / cm 2 、3.2mΩ / cm 2 、3.3mΩ / cm 2 、3.4mΩ / cm 2 、3.5mΩ / cm 2 、3.6mΩ / cm 2 、3.7mΩ / cm 2 、3.8mΩ / cm 2 、3.9mΩ / cm 2 、4mΩ / cm 2 、4.1mΩ / cm 2 、4.2mΩ / cm 2 、4.3mΩ / cm 2 、4.4mΩ / cm 2 、4.5mΩ / cm 2 、4.6mΩ / cm 2 、4.7mΩ / cm 2 、4.8mΩ / cm 2 、4.9mΩ / cm 2 、5mΩ / cm 2 。

[0068] In this article, the TLM test method is used to test the contact resistivity between the first electrode 3 and the first doping region 2. The test principle is based on the TLM (Transfer Length Method) technology. The TLM technology is to prepare a series of electrodes of different lengths on the material and then measure the resistance between the electrodes to infer the conductive properties of the material. The working principle of the TLM tester is to use the fact that the current will be affected by the resistance during the transmission between the electrodes, and the conductive properties of the material can be obtained by measuring the resistance value. When the current is transmitted between the electrodes, it will be affected by the contact resistance of the electrodes and the body resistance of the material itself. The TLM tester can separate the influence of these two parts by measuring the resistance value between the electrodes.

[0069] Since LECO technology is used in the preparation process of the battery, the contact resistivity between the first electrode 3 and the first doping region 2 is reduced compared with the prior art. Therefore, the doping concentration of the activated element and the doping concentration of the inactivated element in the first doping region 2 are correspondingly reduced while the battery performance remains unchanged.

[0070] In the present application, the ratio of the contact area between the first electrode 3 and the first doping region 2 to the orthographic projection area of ​​the first doping region 2 on the substrate is (0.5-2):1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, etc.

[0071] In this way, the contact between the first electrode 3 and the first doping region 2 can be ensured, that is, the contact resistivity can be reduced, so that the battery has good metal-semiconductor contact, which is beneficial to current collection.

[0072] The orthographic projection area of ​​the first doping region 2 on the substrate can be measured by a microscope to measure its one-dimensional size, thereby calculating its area. The one-dimensional size can be the length and the width.

[0073] The contact area between the first electrode 3 and the first doping region 2 is the sum of the effective contact surface and the invalid contact area. The first electrode can be removed by acid etching solution, and then 3D scanning is performed to calculate the contact area (i.e., the total area) between the first electrode 3 and the first doping region 2. The surface area of ​​the irregular region after removing the first electrode is the invalid contact area, and the total area minus the invalid contact area is the effective contact area.

[0074] The ratio of the effective contact area between the first electrode 3 and the first doping region 2 to the contact area between the first electrode 3 and the first doping region 2 is (0.5-0.9):1, for example, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, etc. The larger the effective contact area, that is, the smaller the ineffective contact, the less metal recombination can be reduced, thereby improving the passivation effect of the battery to increase the open circuit voltage.

[0075] In the present application, the first surface corresponding to the first doping region 2 is a polished surface, and has a first tower base-like texture structure on the polished surface; the first tower base-like texture structure includes a plurality of first tower bases;

[0076] The first tower base may be in a truncated cone or a prism shape, and its orthographic projection on the first surface may be a circle, a triangle, a quadrilateral, a pentagon, a hexagon, or an n-gon.

[0077] When the first tower base is truncated cone-shaped, the diameter of the surface of the first tower base close to the first surface is 0.5-1.5 μm, and the diameter of the surface away from the first surface is 1-5 μm. The diameter of the tower base can be measured by 3D scanning.

[0078] Under a 20x microscope, in an area of ​​650μm×650μm, the number of quadrilaterals of the first tower base on the substrate is 1-10. In the battery preparation process, the polishing process of the first surface corresponding to the first doping region 2 is not mirror polishing. Due to the different corrosion rates of silicon in different crystal directions in the alkali solution, a tower base-like texture structure is formed. The concentration and temperature of the alkali solution, the etching time, and different additives can be controlled to reduce the activity of the alkali solution and the size of the bubbles generated, and the speed can be controlled to control the size of the tower base.

[0079] The height of the first tower base is 0-0.3μm, and does not include 0. For example, it can be 0.3μm, 0.29μm, 0.28μm, 0.27μm, 0.26μm, 0.25μm, 0.24μm, 0.23μm, 0.22μm, 0.21μm, 0.2μm, 0.19μm, 0.18μm, 0.17μm, 0.16μm, 0.15μm, 0.14μm, 0.13μm, 0.12μm, 0.11μm, 0.1μm, 0.09μm, 0.08μm, 0.07μm, 0.06μm, 0.05μm, 0.04μm, 0.03μm, 0.02μm, 0.01μm, etc.

[0080] If the first tower base is too high or there are too many first tower bases, the roughness of the first surface will increase and the surface will be uneven, affecting the quality of the subsequent film layer stacked above it; if the first tower base is too small, the density of the first tower base will increase, which will affect the quality of the subsequent film layer stacked above it. At the same time, the appropriate size of the first tower base correspondingly reduces the doping concentration of the activated element and the doping concentration of the non-activated element in the first doping region, thereby better matching the corresponding LECO process.

[0081] The sheet resistance of the first doped region 2 is 200 ohm-500 ohm, for example, 200 ohm, 250 ohm, 300 ohm, 350 ohm, 400 ohm, 450 ohm, 500 ohm, etc.

[0082] Sheet resistance, also known as film resistance, is a measurement value used to indirectly characterize the thermal infrared performance of vacuum coatings on samples such as thin film layers and glass coating layers. The value can be directly converted into thermal infrared emissivity. The size of the sheet resistance is independent of the sample size. Its unit is Siements / sq, and the ohm / sq representation method is added later. The unit is directly translated into sheet resistance or surface resistance. It is also called film layer resistance when used for film layer measurement.

[0083] Within a depth range of 0.1-0.4μm from the first surface, the first doping region 2 has a maximum doping concentration of the activation element; that is, the distance between the position where the maximum doping concentration of the activation element in the first doping region 2 is located and the first surface is 0.1-0.4μm, for example, it can be 0.1μm, 0.12μm, 0.15μm, 0.17μm, 0.2μm, 0.22μm, 0.25μm, 0.27μm, 0.3μm, 0.32μm, 0.35μm, 0.37μm, 0.4μm, etc.

[0084] The closer the location of the maximum doping concentration of the active element is to the first surface, the closer the inactive element is to the first surface; the higher the doping concentration of the inactive element on the first surface, the easier it is to form a strong recombination area, and it is difficult to remove, resulting in a decrease in battery performance. In the present application, the location of the maximum doping concentration of the active element can achieve the best passivation effect and contact effect.

[0085] The junction depth of the first doping region 2 is 1-1.5 μm, for example, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, etc.

[0086] The difference between the depth of the maximum doping concentration position from the first surface and the depth of the junction depth from the first surface is 0.9-1.3 μm, for example, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, etc.

[0087] The doping concentration of the activated element on the first surface corresponding to the first doping region 2 is 1E18-7E18, for example, it can be 1E18, 2E18, 3E18, 4E18, 5E18, 6E18 or 7E18.

[0088] In this application, if Figure 1 As shown, the first surface corresponding to the first doping region 2 has a velvet structure, which is a first pyramid-shaped texture structure. The height of the first pyramid-shaped texture structure is 0.5-3μm, for example, it can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, etc. During the preparation of the battery, the height of the first pyramid-shaped texture structure is 0.5-3μm. At this height, when preparing the first doping area, the diffusion process of the doping element has the least impact on the first pyramid-shaped texture structure. The first pyramid-shaped texture structure can not only take into account the reflectivity, but also bring a smaller tip area and a smaller high-recombination area of ​​metal contact in the subsequent preparation of the first electrode contact process.

[0089] Within a depth range of 0.05-0.3μm from the first surface, the first doping region 2 has a maximum doping concentration of the activation element, that is, the distance between the position where the maximum doping concentration of the activation element in the first doping region 2 is located and the first surface is 0.05-0.3μm, for example, it can be 0.05μm, 0.06μm, 0.07μm, 0.08μm, 0.09μm, 0.1μm, 0.11μm, 0.12μm, 0.13μm, 0.14μm, 0.15μm, 0.16μm, 0.17μm, 0.18μm, 0.19μm, 0.2μm, 0.21μm, 0.22μm, 0.23μm, 0.24μm, 0.25μm, 0.26μm, 0.27μm, 0.28μm, 0.29μm, 0.3μm, etc.

[0090] The maximum doping concentration of the activation element plays a major role in the subsequent formation of the contact between the first electrode and the first doping region. Within the depth range where the maximum doping concentration of the activation element is located, the first electrode and the first doping region achieve an optimal contact resistivity, which is beneficial to the collection of photogenerated current. The distance between the position where the maximum doping concentration is located in the first doping region 2 and the first surface is 0.05-0.3μm. Within this depth range, the transmission gain of the activation element is the largest, and the near-surface recombination loss caused by the inactive element is the smallest.

[0091] The junction depth of the first doping region 2 is 0.8-1.2 μm, for example, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, etc.

[0092] The difference between the depth of the maximum doping concentration of the activation element from the first surface and the depth of the junction from the first surface is 0.5-0.8 μm, for example, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, etc.

[0093] The area from the location of the maximum doping concentration of the activation element to the first surface and the area from the maximum doping concentration of the activation element to the substrate are the two most important areas involved in conduction, but the area from the location of the maximum doping concentration of the activation element to the first surface has the greatest impact on recombination. Therefore, the ratio of the depth from the location of the maximum doping concentration of the activation element to the first surface to the entire junction depth is adjusted to minimize the impact of surface recombination while ensuring contact.

[0094] The doping concentration of the activated element on the first surface corresponding to the first doping region 2 is 1E18-7E18, for example, it can be 1E18, 2E18, 3E18, 4E18, 5E18, 6E18 or 7E18.

[0095] In this application, if Figure 3 As shown, a first passivation layer and a first electrode 3 are provided on a side of the first doping region 2 away from the second surface, the first passivation layer covers the first doping region 2, the first electrode 3 includes a collector electrode 9 extending along the second direction and arranged along the first direction, a portion of the collector electrode 9 passes through the first passivation layer along the second direction and contacts the first doping region 2, the second direction intersects with the first direction, and in some embodiments, the first direction is perpendicular to the second direction. Such a design can prevent excessive metal in the first electrode from entering the substrate, diffusing downward or to both sides, and causing greater metal composite losses.

[0096] The first electrode 3 further includes an interconnection 10, which is electrically connected to the collector electrode 9 and arranged along the second direction; the interconnection 10 is located on the surface of the first passivation layer away from the first doping region 2, and the collector electrode 9 includes a collector electrode portion, which is adjacent to the boundary between the interconnection 10 and the collector electrode 9 along the second direction, and is located on the surface of the first passivation layer away from the first doping region 2, or is located in the first passivation layer; along the second direction, the size of the collector electrode portion is less than or equal to one third of the spacing between adjacent interconnections 10. The interconnection portion can prevent the first electrode with more intersections from damaging the contact between the first passivation layer and the first doping region below, causing more serious metal recombination.

[0097] The first electrode 3 also includes a main electrode 8, which extends along the first direction and is arranged along the second direction. The main electrode 8 is connected to the collector electrode 9 through an interconnection 10. The size of the interconnection can be greater than or equal to the size of the collector electrode. When the size of the interconnection 10 is equal to the size of the collector electrode 9, a non-welding process can be used to achieve the interconnection of the back contact battery, such as a coating process, in which a carrier film with a conductive interconnection is directly attached to the surface of the back contact battery, and pressed to form an electrical interconnection. For another example: the interconnection 10 can be a bus electrode, or it can be an interconnection arranged on the bus electrode.

[0098] In this article, the size of the interconnection can be its length, width or diameter. The size of the collector electrode can be its length, width or diameter. For example, the width of the interconnection can be greater than the width of the collector electrode. For example, the length of the interconnection can be equal to the length of the collector electrode.

[0099] In the present application, both the active elements and the inactive elements are Group IIIA elements or Group VA elements.

[0100] The active element and the inactive element are the same doping element.

[0101] In some embodiments, both the active element and the non-lasing element are boron.

[0102] In the present application, the battery also includes a second doping region, which is located on the first surface, the first doping region 2 and the second doping region are arranged alternately, and the conductivity type of the second doping region is opposite to that of the first doping region 2; the first surface corresponding to the first doping region 2 is a first tower base-like texture structure; the first surface corresponding to the second doping region has a second tower base-like texture structure; the second tower base-like texture structure includes multiple second tower bases.

[0103] During the battery preparation process, the polishing process of the first surface corresponding to the second doped area is not mirror polishing. Due to the different corrosion rates of silicon in different crystal orientations in the alkaline solution, a tower base-like texture structure is formed. The concentration and temperature of the alkaline solution, the etching time, and different additives can be controlled to reduce the activity of the alkaline solution and the size of the bubbles generated. The speed can be controlled to control the size of the tower base.

[0104] The number and size of the second tower bases per unit area can be determined according to actual needs. If the number of the second tower bases per unit area is too large, the roughness of the first surface will increase, the surface will be uneven, and the quality of the subsequent film layer stacked thereon will be affected. If the number of the second tower bases is too small, the density of the second tower bases will increase, thereby affecting the quality of the subsequent film layer stacked thereon.

[0105] The one-dimensional size of the second tower base is greater than or equal to the one-dimensional size of the first tower base;

[0106] The one-dimensional dimension of the second tower base is the dimension of the surface of one side of the second tower base away from the base;

[0107] Under this matching, when preparing the first doping region, the diffusion process of the doping element has the least effect on the first pyramid texture structure. The first pyramid texture structure can take into account the reflectivity and bring a smaller tip area and a smaller high composite area of ​​metal contact in the subsequent preparation of the contact process of the first electrode. At the same time, the appropriate pyramid size correspondingly reduces the doping concentration of the activated element and the doping concentration of the non-activated element in the first doping region, thereby better matching the corresponding LECO process. The second doping region adopts a second tower base structure. The second tower base is too high, resulting in a larger roughness of the first surface corresponding to the second doping region, and the surface is uneven, which affects the quality of the subsequent film layer stacked above it; if the second tower base is too small, the density of the second tower base will increase, which will affect the quality of the subsequent film layer stacked above it. In this article, the one-dimensional size can be specifically determined according to the shape of the orthographic projection of the second tower base on the substrate. For example, when the orthographic projection of the second tower base on the substrate is a circle, the one-dimensional size refers to the diameter of the circle; when the orthographic projection of the second tower base on the substrate is a rectangle, the one-dimensional size can be the diagonal length or length of the rectangle.

[0108] The height of the second tower foundation is less than or equal to the height of the first tower foundation.

[0109] The film layers formed on the surfaces of the first tower base and the second tower base are different, so different requirements are placed on the morphology of the tower base. For the second doping region, the size of the second tower base needs to be as small as possible to ensure that the tunneling layer prepared on this morphology has higher quality. However, for the first doping region, the first tower base with certain undulations can increase the area of ​​the first doping region. At the same time, the morphology of the first tower base will affect the morphology of the second tower base. The first tower base is prepared first, and the second tower base corresponding to the second doping region is prepared on the basis of the first tower base.

[0110] The first tower base needs to consider reducing the current loss caused by reflection to the greatest extent, while the second tower base needs to consider the composite loss in the transmission process caused by the collection process to the greatest extent. Because the texturing process is not a very uniform process, in actual effect, the height of the second tower base is less than or equal to the height of the first tower base. At this time, the number of tower bases is reduced, and the composite loss caused by the transmission process is minimized.

[0111] In the present application, the battery also includes a second doping region, which is located on the first surface, and the first doping region 2 and the second doping region are arranged alternately; the conductivity type of the second doping region is opposite to that of the first doping region 2; the first surface corresponding to the first doping region 2 has a first pyramid-shaped texture structure, and the first surface corresponding to the second doping region has a second tower base-shaped texture structure; the second tower base-shaped texture structure includes multiple second tower bases.

[0112] During the battery preparation process, the polishing process of the first surface corresponding to the second doped area is not mirror polishing. Due to the different corrosion rates of silicon in different crystal orientations in the alkaline solution, a tower base-like texture structure is formed. The concentration and temperature of the alkaline solution, the etching time, and different additives can be controlled to reduce the activity of the alkaline solution and the size of the bubbles generated. The speed can be controlled to control the size of the tower base.

[0113] The number and size of the second tower bases per unit area can be determined according to actual needs. If the number of the second tower bases per unit area is too large, the roughness of the first surface will increase, the surface will be uneven, and the quality of the subsequent film layer stacked thereon will be affected. If the number of the second tower bases is too small, the density of the second tower bases will increase, thereby affecting the quality of the subsequent film layer stacked thereon.

[0114] The one-dimensional size of the second tower base is smaller than the one-dimensional size of the tower bottom of the first pyramid-shaped texture structure; the one-dimensional size of the second tower base is the size of the surface of one side of the second tower base away from the base;

[0115] The one-dimensional size of the bottom of the first pyramid-shaped texture structure is the one-dimensional size of the figure of the orthographic projection of the bottom of the first pyramid-shaped texture structure on the base.

[0116] The height of the second tower base is smaller than the height of the first pyramid-shaped texture structure, which is beneficial for preparing a gap area that is easy to passivate.

[0117] In the present application, the battery further includes a second doping region and a first passivation layer, the second doping region is located on the first surface, the first doping region 2 and the second doping region are arranged alternately; the second doping region is opposite to the first doping region 2 in conductivity type; there is a gap region between the first doping region 2 and the second doping region; the roughness of the first surface corresponding to the gap region is 0-1 μm, for example, it can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm; the first passivation layer covers the gap region. The passivation of the first surface of the spacer region is achieved by the field passivation and hydrogen passivation of the first passivation layer (aluminum oxide and silicon nitride), but excessive roughness will result in poor film quality of the first passivation layer.

[0118] The width of the gap region is 10 μm-60 μm, for example, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, etc.

[0119] In some embodiments, the first surface corresponding to the first doping region 2 is a first tower base-shaped texture structure; the height difference between the first surface corresponding to the gap area and the first surface corresponding to the first doping region 2 is 0.5-6μm, for example, it can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, etc.

[0120] In some embodiments, the first surface corresponding to the first doping region 2 is a first pyramid-shaped texture structure; the height difference between the first surface corresponding to the gap region and the first surface corresponding to the first doping region 2 is 0.5-8 μm, for example, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 6μm, 7μm, 7.5μm, 8μm, etc.

[0121] The passivation of the first surface of the spacing region is achieved through the field passivation and hydrogen passivation of the first passivation layer (aluminum oxide and silicon nitride). The first surface of the spacing region is lower than the first surface of the first doping region 2, thereby forming a pit in the gap region, which can increase the contact area between the first surface of the gap region and the aluminum oxide and hydrogen, and the passivation surface is suspended, thereby strengthening the passivation of the first surface. When the pit is too deep, the corresponding aluminum oxide in this area will also be relatively thin, so the aluminum oxide passivation effect will be worse; when the pit is too shallow, during the battery preparation process, the original first doping region in the pit cannot be completely removed, and when preparing the second doping region, the residue will form a high-strength composite center with the new diffusion layer.

[0122] In the present application, the second doped region includes a tunneling layer 5 and a second silicon-containing doped layer; one side surface of the tunneling layer 5 is stacked on the first surface of the substrate, and the other side surface thereof is stacked on the second silicon-containing doped layer.

[0123] The second silicon-containing doped layer may be one of an n-type doped polycrystalline silicon layer, an n-type doped amorphous silicon layer, an n-type doped microcrystalline silicon layer, and an n-type doped silicon carbide layer, including but not limited to these.

[0124] The thickness of the second silicon-containing doped layer is 50nm-400nm, for example, it can be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, 210nm, 220nm, 230nm, 240nm, 250nm, 260nm, 270nm, 280nm, 290nm, 300nm, 310nm, 320nm, 330nm, 340nm, 350nm, 360nm, 370nm, 380nm, 390nm, 400nm, etc.

[0125] The roughness of the first surface corresponding to the second doping region is less than or equal to 0.5 μm, that is, the roughness of the silicon substrate 1 at the junction with the tunneling layer 5 is less than or equal to 0.5 μm, for example, it can be 0.5 μm, 0.49 μm, 0.48 μm, 0.47 μm, 0.46 μm, 0.45 μm, 0.44 μm, 0.43 μm, 0.42 μm, 0.41 μm, 0.40 μm, 0.39 μm, etc. In some embodiments, the roughness of the first surface corresponding to the second doping region is less than or equal to 0.45 μm; the roughness of the first surface corresponding to the second doping region is less than or equal to 0.4 μm. Low roughness is conducive to growing a denser tunneling layer, so that the tunneling layer has better chemical passivation and transmission effects.

[0126] In this article, roughness refers to the difference between the highest point and the lowest point. Roughness can be measured using 3D scanning.

[0127] Specifically, the solar cell is a BC cell, and a second doping region is stacked on the first surface of the substrate, and the second doping region and the first doping region 2 are sequentially arranged on the first surface. The second doping region includes a tunneling layer 5 and a second silicon-containing doping layer 4 stacked in sequence, and the tunneling layer 5 is stacked with the substrate, and a second electrode 6 is arranged on the second silicon-containing doping layer 4; the second silicon-containing doping layer 4 has a conductivity type opposite to that of the first doping region 2, the doping element in the first doping region 2 is boron, and the doping element in the second silicon-containing doping layer 4 is phosphorus. The substrate is a silicon substrate 1.

[0128] A second passivation layer is stacked on the second surface of the silicon substrate 1, and a first passivation layer covering the second silicon-containing doped layer 4 and the first doped region 2 is stacked on the surface of the second silicon-containing doped layer 4 facing away from the silicon substrate 1, and the first electrode 3 penetrates the second passivation layer and extends into the first doped region 2, and the second electrode 6 penetrates the second passivation layer and contacts the second silicon-containing doped layer 4.

[0129] There is a gap region between the first doping region 2 and the second doping region, and the width of the gap region is 10 μm-60 μm.

[0130] The roughness of the first surface of the silicon substrate 1 in the spacing region is 0-1 μm, for example, 0, 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1 μm, etc.

[0131] The roughness of the first surface of the silicon substrate 1 stacked with the tunneling layer 5 is 0-0.5 μm, for example, 0 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, etc.

[0132] The silicon substrate 1 may be an n-type silicon substrate 1 or a p-type silicon substrate 1 .

[0133] In some embodiments, the light-facing surface of the silicon substrate 1 has a suede structure, and the backlight surface is a polished surface.

[0134] In some embodiments, both the light-facing surface and the backlight surface of the silicon substrate 1 have a suede structure.

[0135] In some embodiments, part of the backlight surface of the silicon substrate 1 is a suede structure, and part of the backlight surface is a polished surface.

[0136] The thickness of the first doping region 2 is 400nm-3μm, for example, it can be 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 900nm, 950nm, 1μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm, 2μm, 2.2μm, 2.4μm, 2.6μm, 2.8μm, 3μm, etc.

[0137] The second silicon-containing doped layer 4 may be one of an n-type doped polycrystalline silicon layer, an n-type doped amorphous silicon layer, an n-type doped microcrystalline silicon layer, and an n-type doped silicon carbide layer, including but not limited to these.

[0138] The thickness of the second silicon-containing doped layer 4 is 50 nm-400 nm.

[0139] The tunneling layer 5 is a silicon oxide layer with a thickness of 1-2 nm.

[0140] The first passivation layer includes a silicon nitride layer (SiNx, x can be any value) and an aluminum oxide layer (AlOx, x can be any value) stacked in sequence, wherein a surface of the silicon nitride layer away from the aluminum oxide layer is stacked with the silicon substrate 1 .

[0141] The thickness of the silicon nitride layer is 50nm-130nm, and the thickness of the aluminum oxide layer is 2nm-15nm.

[0142] The second passivation layer includes a silicon nitride layer (SiNx, x can be any value) and an aluminum oxide layer (AlOx, x can be any value) stacked in sequence, wherein the surface of the silicon nitride layer away from the aluminum oxide layer is stacked together with the first doped region 2 and the second silicon-containing doped layer 4.

[0143] The thickness of the silicon nitride layer is 50nm-130nm, and the thickness of the aluminum oxide layer is 2nm-15nm.

[0144] The first electrode 3 and the second electrode 6 can be made of silver, copper, aluminum, or alloys thereof. The first electrode 3 and the second electrode 6 can be the same or different.

[0145] In the present application, the battery also includes a second doping region, the second doping region is located on the second surface, the second doping region includes a tunneling layer 5 and a second silicon-containing doping layer 4 stacked in sequence, and the first doping region 2 has an opposite conductivity type to the second doping region.

[0146] Specifically, when the solar cell is a TOPcon cell, the second surface of the substrate has a tunneling layer 5, a second silicon-containing doped layer 4 and a second electrode 6 stacked in sequence, the second surface has a third tower-shaped texture structure, and the first doped region 2 has an opposite doping type to the second silicon-containing doped layer 4. The first surface of the substrate has a first doped region 2, a first electrode 3 is arranged on the first doped region 2, a first passivation layer is stacked on the surface of the first doped region 2 on the side away from the substrate, a second passivation layer is stacked on the surface of the second silicon-containing doped layer 4 on the side away from the substrate, the first electrode 3 penetrates the first passivation layer and is connected to the first doped region 2, and the second electrode 6 penetrates the second passivation layer and is connected to the second silicon-containing doped layer 4.

[0147] The first pyramid-shaped texture structure can take into account the reflectivity and bring about a smaller tip area and a smaller high-recombination area of ​​the metal contact in the subsequent process of preparing the contact of the first electrode. At the same time, the appropriate pyramid size correspondingly reduces the doping concentration of the activated element and the doping concentration of the non-activated element in the first doping region, thereby better matching the corresponding LECO process. The second surface has a third tower base-shaped texture structure. If the third tower base is too high, the roughness of the first surface corresponding to the second doping region becomes larger, and the surface is uneven, which affects the quality of the subsequent film layer stacked thereon; if the third tower base is too small, the density of the third tower base will increase, which will affect the quality of the subsequent film layer stacked thereon.

[0148] For the description of the substrate, the second silicon-doped layer 4 , the first passivation layer and the second passivation layer, the first electrode 3 and the second electrode 6 , reference may be made to the description of the aforementioned BC battery.

[0149] The present application provides a method for preparing a solar cell, comprising the following steps:

[0150] Providing a substrate; the substrate having a first surface and a second surface disposed opposite to each other;

[0151] The doping element enters the substrate from the first surface of the substrate, thereby forming a first doping region 2;

[0152] In the first doping region 2, the doping concentration of the inactive element is 1E19~1E22, and the doping concentration of the active element is 1E17~8E18. In the first doping region 2, in the direction from close to the first surface to the inside of the substrate, the doping concentration of the active element first increases and then decreases, and the difference between the maximum doping concentration of the active element and the doping concentration of the active element at the first surface is 1E18~7E18.

[0153] After the first doping region 2 is formed, a first electrode 3 is formed on the first doping region 2 , and the first electrode 3 at least partially extends into the first doping region 2 .

[0154] In the step of forming the first electrode 3 , a first electrode precursor is formed first, and then the first electrode precursor and the first doping region 2 are processed by using a LECO process.

[0155] LECO (Laser-enhanced contact optimization), also known as laser enhanced contact optimization, is an advanced laser sintering technology that can locally destroy the passivation layer in a very precise manner and promote electron transfer between metal electrodes and silicon. The LECO process applies high-intensity laser pulses locally on the front or back of the solar cell and maintains a constant reverse voltage. The resulting local current significantly reduces the contact resistivity between the semiconductor and the metal electrode.

[0156] When the first surface corresponding to the first doping region 2 has a first pyramid-shaped texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the highest points of two adjacent spires in the first pyramid-shaped texture structure.

[0157] When the first surface corresponding to the first doping region 2 has a first tower-shaped texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between two adjacent first tower-shaped texture structures.

[0158] Specifically, when the solar cell is a BC cell, the method for preparing the solar cell comprises the following steps:

[0159] Step 1: providing a silicon substrate 1; the silicon substrate 1 has a first surface and a second surface arranged opposite to each other;

[0160] Step 2: Polishing or texturing the first surface (backlight surface) of the silicon substrate 1 to diffuse the doping elements, thereby forming the first doping region 2 .

[0161] Step 3: first patterning to form a patterned first doping region 2.

[0162] The first patterning is performed by a conventional method, which is not specifically limited, such as laser grooving or masking.

[0163] When laser grooving is used for imaging, the unit energy density of the laser can be adjusted specifically. By adjusting the power, frequency, speed, and type of light source of the laser, the energy density can be adjusted to 0.3J / m 3 -2 J / m 3 The reflectivity of the light in the laser band on this kind of battery structure is adjusted. The reflectivity on the velvet surface is 1%-5%, and the reflectivity on the polished surface is 5%-25%. At this time, the best film removal effect and low damage effect are achieved. The judgment standard is the PL test. The PL measurement after laser drops to 1%-5%.

[0164] When the mask method is used, the mask is an oxide with a thickness of 5nm-100nm, the main component of which is silicon oxide, and the proportion of boron in the oxide is 0-20%, or it is matched with other masking films, such as commonly used wax printing or offset printing, etc. The main advantage is that the masking film of this component can be completely removed in less than 120S under low concentration HF (1%-5%), or completely removed in 240S under low concentration alkali NaOH or KOH (2%-10%), without using additives and introducing other impurities.

[0165] After the first patterning is completed, a plurality of first doped regions 2 are provided at intervals on the first surface of the silicon substrate 1, and the exposed silicon substrate forms a polished surface.

[0166] Step 4: forming a whole layer of tunneling layer 5 and second silicon-containing doped layer 4 on a surface of the first doped region 2 away from the silicon substrate 1 and the exposed silicon substrate 1 .

[0167] The preparation processes of the tunneling layer 5 and the second silicon-doped layer 4 are conventional and are not further limited here. For example, the tunneling layer 5 can be formed by POLY, and the second silicon-doped layer 4 can be formed by LPCVD.

[0168] Step 5: Second patterning: forming a patterned tunneling layer 5 and a second silicon-doped layer 4 .

[0169] The second patterning is performed by a conventional method, which is not specific and limited, such as laser grooving + cleaning or masking.

[0170] In the second patterning process, the tunneling layer 5 and the second silicon-containing doped layer 4 on the first doped region 2 are removed, and the tunneling layer 5 and the second silicon-containing doped layer 4 in the gap region between the first doped region 2 and the second silicon-containing doped layer 4 are removed.

[0171] Step 6: A passivation layer 7 is formed on the second surface (light-facing surface) of the silicon substrate 1 and the surface of the second silicon-containing doped layer 4 away from the silicon substrate 1. The passivation layer 7 located on the light-facing surface of the silicon substrate 1 is the second passivation layer, and the passivation layer 7 located on the first doped region 2 and the second silicon-containing doped layer 4 is the first passivation layer. The preparation process of the passivation layer 7 is conventional and is not further limited here. For example, the passivation layer can be formed by a pecvd method.

[0172] Step 7: forming the first electrode 3 and the second electrode 6.

[0173] First, a first electrode precursor is formed on the surface of the first passivation layer facing away from the first doping region by using a screen printing process, and a second electrode is formed on the surface of the first passivation layer facing away from the second doping region. Then, the first electrode 3 and the first doping region 2 are processed by using a LECO process, thereby forming a first electrode 3 and a second electrode 6 penetrating the first passivation layer on the first passivation layer, wherein the first electrode 3 partially penetrates the first passivation layer and extends into the first doping region 2, and the second electrode 6 penetrates the first passivation layer and contacts the second silicon-containing doping layer 4.

[0174] The laser in the LECO process is green light or infrared light, the reverse bias voltage is between 2V and 15V, and the scanning mode is front scanning or back scanning.

[0175] When the first surface corresponding to the first doping region 2 has a first pyramid-shaped texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the highest points of the two spires in the first pyramid-shaped texture structure.

[0176] When the first surface corresponding to the first doping region 2 has a first tower base-shaped texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the geometric centers of two adjacent first tower bases in the first tower base-shaped texture structure. The LECO process can improve the contact performance between the first electrode 3 and the first doping region 2, thereby improving the electrical performance of the battery. Compared with the prior art that does not use the LECO process, the series resistance of the solar cell of the present application is reduced, the FF is improved, the open circuit voltage is improved, and the battery efficiency is improved.

[0177] Specifically, when the solar cell is a TOPcon cell, the method for preparing the solar cell comprises the following steps:

[0178] Step 1: providing a silicon substrate 1; the silicon substrate 1 has a first surface and a second surface arranged opposite to each other;

[0179] Step 2: diffusing doping elements on the first surface (light-facing surface) of the silicon substrate 1 to form a first doping region 2;

[0180] Step 3: forming a tunneling layer 5 and a second silicon-containing doped layer 4 in sequence on the second surface (backlight surface) of the silicon substrate 1;

[0181] Step 4: forming a first passivation layer on a surface of the first doped region 2 facing away from the silicon substrate 1 , and forming a second passivation layer on a surface of the second silicon-containing doped layer 4 facing away from the silicon substrate 1 .

[0182] Step 5: forming a second electrode 6 on a surface of the second passivation layer away from the silicon substrate 1, and the second electrode 6 passes through the second passivation layer and is connected to the second silicon-containing doped layer 4; at the same time, forming a first electrode precursor on a surface of the first passivation layer away from the first doped region by a screen printing process, and then treating the first electrode 3 and the first doped region 2 by a LECO process,

[0183] The LECO process can improve the contact performance between the first electrode 3 and the first doping region 2, thereby improving the electrical performance of the battery. Compared with the prior art without the LECO process, the solar cell of the present application has a reduced series resistance, increased FF, increased open circuit voltage, and improved battery efficiency.

[0184] When the first surface corresponding to the first doping region 2 has a first pyramid-shaped texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the highest points of the two spires in the first pyramid-shaped texture structure.

[0185] When the first surface corresponding to the first doping region 2 has a first tower base-shaped texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the geometric centers of two adjacent first tower bases in the first tower base-shaped texture structure. The LECO process can improve the contact performance between the first electrode 3 and the first doping region 2, thereby improving the electrical performance of the battery. Compared with the prior art that does not use the LECO process, the series resistance of the solar cell of the present application is reduced, the FF is improved, the open circuit voltage is improved, and the battery efficiency is improved.

[0186] The solar cell prepared by the preparation method of the present application is the aforementioned solar cell.

[0187] The present application provides a photovoltaic assembly, comprising the aforementioned solar cell.

[0188] The present application provides a photovoltaic system, comprising the aforementioned photovoltaic component.

[0189] Example

[0190] The experimental methods used in the following examples are all conventional methods unless otherwise specified.

[0191] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0192] Example 1

[0193] The BC solar cell of this embodiment includes the following steps:

[0194] Step 1: providing a silicon substrate 1; the silicon substrate has a first surface and a second surface arranged opposite to each other;

[0195] The single crystal silicon wafer is an N-type silicon wafer, and a texturing and cleaning procedure is performed on both sides of the N-type silicon wafer so that the first surface has a first pyramid-shaped texture structure, and the height of the first pyramid-shaped texture structure is 1-3 μm.

[0196] Step 2: Boron is used to diffuse doping elements on the first surface (backlight surface) of the silicon substrate 1, thereby forming a first doping region 2. In the first doping region 2, the minimum doping concentration of the boron element in the non-activated state is 1E19, the maximum doping concentration is 1E22 within a depth range of 0.3 μm from the first surface, and the doping concentration at the first surface is 5E20, the minimum doping concentration of the boron element in the activated state is 1E17, the maximum doping concentration is 8E18 within a depth range of 0.3 μm from the first surface, and the doping concentration at the first surface is 5E18, and in the first doping region 2, in the direction from the first surface to the substrate, the doping concentration of the boron element in the activated state first increases and then decreases, and the difference between the maximum doping concentration of the boron element in the activated state and the doping concentration of the activated element at the first surface is 3E18; the junction depth of the first doping region 2 is 0.8 μm; the square resistance of the first doping region 2 is 200 ohms.

[0197] Step 3: first patterning to form a patterned first doping region 2.

[0198] When laser grooving is used for imaging, the first laser is used to irradiate the other areas on the first surface except the first doped area 2 to be retained, and the first doped area 2 in other areas except the first doped area 2 to be retained is etched away, thereby exposing the silicon substrate. The first laser is a picosecond laser with an energy density of 200MJ / m 2 After the first patterning is completed, a plurality of first doping regions 2 are arranged at intervals on the first surface of the silicon substrate 1. The width of the first doping region 2 is 250 μm, and the exposed silicon substrate is a second tower-shaped texture structure.

[0199] Step 4: Form a tunneling layer 5 and a second silicon-containing doped layer 4 on the surface of the first doped region 2 away from the silicon substrate 1. The tunneling layer 5 can be formed by POLY, and the second silicon-containing doped layer 4 can be formed by LPCVD. The tunneling layer 5 is a silicon oxide layer with a thickness of 2 nm. The second silicon-containing doped layer 4 is a phosphorus-doped polysilicon layer with a thickness of 100 nm.

[0200] Step 5: Second patterning: forming a patterned tunneling layer 5 and a second silicon-doped layer 4 .

[0201] A second laser is used to irradiate the first doped region 2 and the second silicon-containing doped layer corresponding to the preset gap region. The instantaneous high temperature of the laser has a film-opening effect, and then the second silicon-containing doped layer and the tunneling layer just above the first doped region and the second silicon-containing doped layer and the tunneling layer in the gap region are etched away, thereby forming a patterned tunneling layer 5 and a second silicon-containing doped layer 4.

[0202] The second laser is a picosecond laser with an energy density of 200MJ / m 2 .

[0203] The width of the second silicon-containing doped layer 4 and the tunneling layer 5 is 250 μm.

[0204] The height difference between the first surface corresponding to the gap region and the first surface corresponding to the first doping region 2 is 2 μm; the height difference between the first surface corresponding to the tunneling layer 5 and the first surface corresponding to the first doping region 2 is 3 μm;

[0205] The roughness of the first surface corresponding to the gap region is 1 μm;

[0206] The roughness of the first surface corresponding to the second doping region is 0.5 μm.

[0207] Step six: A passivation layer 7 is formed on the second surface (light-facing surface) of the silicon substrate 1 and on the side surface of the second silicon-containing doped layer 4 away from the silicon substrate 1. The passivation layer 7 located on the light-facing surface of the silicon substrate 1 is the second passivation layer, and the passivation layer 7 located on the first doping region 2 and the second silicon-containing doped layer 4 is the first passivation layer. The passivation layer can be formed by pecvd. The passivation layer is a silicon nitride layer and an aluminum oxide layer. The thickness of the silicon nitride layer is 100 nm, and the thickness of the aluminum oxide layer is 5 nm. In the first passivation layer, the side surface of the silicon nitride layer away from the aluminum oxide layer is stacked with the silicon substrate 1. In the second passivation layer, the side surface of the silicon nitride layer away from the aluminum oxide layer is stacked with the first doping region 2 and the second silicon-containing doped layer 4.

[0208] Step 7: forming the first electrode 3 and the second electrode 6.

[0209] First, a screen printing process is used to form a first electrode precursor on the surface of the first passivation layer away from the first doping region, and at the same time, a second electrode is formed on the surface of the first passivation layer away from the second doping region; then the LECO process is used to process the first electrode 3 and the first doping region 2, thereby forming a first electrode 3 and a second electrode 6, the first electrode 3 penetrates the first passivation layer and partially extends into the first doping region 2, and the second electrode 6 penetrates the first passivation layer and connects to the second silicon-containing doping layer 4. The first electrode is silver paste, and the second electrode is silver paste.

[0210] The laser in the LECO process is green light, the reverse bias voltage is 15V, the reverse current is 8A, and the scanning mode is front scanning or back scanning. The diameter of the laser spot used is the distance between the two spires in the first pyramid texture structure. The LECO process can improve the contact performance between the first electrode 3 and the first doping region 2, thereby improving the electrical performance of the battery. Compared with the prior art that does not use the LECO process, the series resistance of the solar cell of the present application is reduced, the FF is improved, the open circuit voltage is improved, and the battery efficiency is improved.

[0211] The performance of the solar cell of this embodiment is shown in Table 1.

[0212] The solar cells of Examples 2-4 differ from the solar cell of Example 1 only in that the parameters in the LECO process are different, specifically, the reverse bias voltage is different.

[0213] The performance of the solar cell of this embodiment is shown in Table 1.

[0214] The solar cells of Example 5 and Comparative Examples 3-4 differ from the solar cell of Example 1 only in that the doping concentration of the maximum activation element in the first doping region is different.

[0215] The performance of the solar cell of this embodiment is shown in Table 1.

[0216] The solar cells of Example 6 and Comparative Example 5 are different from the solar cell of Example 1 only in that the difference between the maximum doping concentration of the activation element in the first doping region and the doping concentration of the activation element at the first surface is different.

[0217] The performance of the solar cell of this embodiment is shown in Table 1.

[0218] The difference between the solar cell of Example 7 and Example 1 is only in step 1 and step 2. Step 1 and step 2 of this embodiment are as follows:

[0219] Step 1: providing a silicon substrate 1; the silicon substrate has a first surface and a second surface arranged opposite to each other;

[0220] The single crystal silicon wafer is an N-type silicon wafer, and the N-type silicon wafer is polished on both sides so that the first surface has a first tower base-shaped texture structure. Under a 20x microscope, in an area of ​​650 μm×650 μm, the number of orthographic projections of the first tower base on the substrate that are quadrilaterals is 1-10, and the height of the first tower base is 0-0.3 μm.

[0221] In step 2: the first surface (backlight surface) of the silicon substrate 1 is diffused with the boron element to form the first doping region 2. In the first doping region 2, the minimum doping concentration of the boron element in the non-activated state is 1E19, the maximum doping concentration is 1E22 within a depth range of 0.35 μm from the first surface, and the doping concentration at the first surface is 5E20, the minimum doping concentration of the boron element in the activated state is 1E17, the maximum doping concentration is 8E18 within a depth range of 0.35 μm from the first surface, and the doping concentration at the first surface is 5E18, and in the first doping region 2, in the direction from the first surface to the substrate, the doping concentration of the boron element in the activated state increases first and then decreases, and the difference between the maximum doping concentration of the boron element in the activated state and the doping concentration of the activated element at the first surface is 3E18; the junction depth of the first doping region 2 is 1.4 μm; the square resistance of the first doping region 2 is 200 ohms.

[0222] The performance of the solar cell of this embodiment is shown in Table 1.

[0223] Comparative Example 1

[0224] The solar cell of this comparative example 1 is different from the solar cell of Example 1 only in that the solar cell is not subjected to the LECO process. The performance of the solar cell of this comparative example is shown in Table 1.

[0225] Comparative Example 2

[0226] The only difference between the solar cell of this comparative example 2 and the solar cell of the embodiment is the first doping region 2. The structure of the first doping region 2 of the solar cell in this comparative example 2 is a first tunneling layer + a first doping layer. The first tunneling layer 5 is silicon oxide with a thickness of 2nm. The first doping layer is a p-type polysilicon doping layer with a thickness of 100nm.

[0227] The performance of the solar cell of this comparative example is shown in Table 1.

[0228] The electrical performance parameters in Table 1 are obtained by testing with an IV tester.

[0229] Table 1 shows the parameters of each embodiment and comparative example.

[0230]

[0231]

[0232] Summary: It can be seen from the above table that the solar cell of the present application, while adopting LECO technology, changes the contact between the first electrode and the first doping region, thereby reducing the contact resistivity between the first electrode and the first doping region. On the basis of taking into account the battery performance, the doping concentration of the activation element and the doping concentration of the non-activation element in the first doping region can be reduced accordingly, and the doping concentration of the activation element can be as low as 1E17~1E19. In Comparative Examples 1-3, since the contact resistivity between the first electrode and the first doping region is relatively high, the battery performance is relatively low. Although the battery efficiency in Comparative Example 4 is relatively high, its Voc value is lower than that in Example 1, so it cannot be used as a high-efficiency battery. Although the battery efficiency in Comparative Examples 5 and Comparative Examples 6 is relatively high, compared with Example 1, the composite is larger and the Voc value is lower, so it cannot be used as a high-efficiency battery.

[0233] Although the embodiments of the present application are described above in conjunction with the accompanying drawings, the present application is not limited to the above specific embodiments and application fields, and the above specific embodiments are merely illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can also make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present application, all of which belong to the protection of the present application.

Claims

1. A solar cell, wherein: comprising a substrate having a first surface and a second surface disposed opposite to each other; A first doping region is located in the substrate and is a region close to the first surface. A second doping region is stacked on the first surface of the substrate. The first doping region and the second doping region are alternately arranged. The second doping region has a conductivity type opposite to that of the first doping region. There is a gap region between the first doping region and the second doping region. The second doped region includes a tunneling layer and a second silicon-containing doped layer stacked in sequence; a side surface of the tunneling layer is stacked with the substrate; The first doping region contains the doping element boron.

2. The solar cell according to claim 1, wherein: A first electrode is disposed on a surface of the first doping region away from the substrate, and a portion of the first electrode extends into the first doping region; The contact resistance between the first electrode and the first doping region is 0.1 to 3 mΩ / cm 2 .

3. The solar cell according to claim 1, wherein: A first passivation layer and a first electrode are arranged on a side of the first doped region away from the second surface, the first passivation layer covers the first doped region, the first electrode includes a collector electrode extending along the second direction and arranged along the first direction, a partial area of ​​the collector electrode passes through the first passivation layer and contacts the first doped region, and the second direction intersects with the first direction.

4. The solar cell according to claim 3, wherein: The first electrode also includes an interconnection portion, which is electrically connected to the collector electrode and is arranged along the second direction; the interconnection portion is located on a surface of the first passivation layer away from the first doping region, and the collector electrode includes a collector electrode portion, which is adjacent to the junction of the interconnection portion and the collector electrode along the second direction, and is located on the surface of the first passivation layer away from the first doping region or in the first passivation layer; along the second direction, the size of the collector electrode portion is less than or equal to one third of the spacing between adjacent interconnections.

5. The solar cell according to claim 3, wherein: The first passivation layer covers the gap region; The roughness of the first surface corresponding to the gap region is 0-1 μm.

6. The solar cell according to claim 1, wherein: The roughness of the first surface corresponding to the second doping region is less than or equal to 0.5 μm.

7. The solar cell according to claim 1, wherein: The doping elements in the first doping region include inactive elements and active elements, the doping concentration of the inactive elements is 1E19~1E22, the doping concentration of the active elements is 1E17~8E18, and in the first doping region, in the direction from the first surface to the substrate, the doping concentration of the active elements first increases and then decreases, and the difference between the maximum doping concentration of the active elements and the doping concentration of the active elements at the first surface is 1E18~7E18.

8. The solar cell according to claim 7, wherein: The first surface corresponding to the first doping region has a first pyramid-shaped texture structure, and the first surface corresponding to the second doping region has a second pyramid-shaped texture structure; the second pyramid-shaped texture structure includes a plurality of second pyramid bases; The one-dimensional size of the second tower base is smaller than the one-dimensional size of the tower bottom of the first pyramid-shaped texture structure; the one-dimensional size of the second tower base is the size of the surface of one side of the second tower base away from the base; The height of the second tower base is smaller than the height of the first pyramid-shaped texture structure.

9. A method for preparing a solar cell, wherein: The steps include: providing a silicon substrate; The silicon substrate has a first surface and a second surface that are arranged opposite to each other; Doping elements enter the silicon substrate from the first surface of the silicon substrate, thereby forming a first doping region; Patterning for the first time, thereby forming a first doped region with a plurality of intervals on the first surface of the silicon substrate, and forming a polished surface on the exposed silicon substrate; Forming a whole layer of tunneling layer and a second silicon-containing doped layer on a surface of the first doped region away from the silicon substrate and the exposed silicon substrate; The second patterning is to remove the tunneling layer and the second silicon-containing doped layer located on the first doped region, and at the same time, the tunneling layer and the second silicon-containing doped layer in the gap region between the first doped region and the second silicon-containing doped layer are removed, thereby forming a patterned tunneling layer and the second silicon-containing doped layer; The first doping region contains the doping element boron.

10. The preparation method according to claim 9, wherein: After forming the first doping region, forming a first electrode on the first doping region, wherein forming the first electrode comprises the following steps: forming a first electrode precursor; The first electrode precursor and the first doping region are processed by using the LECO process.

11. The preparation method according to claim 10, wherein: When the first surface corresponding to the first doping region has a first pyramid-shaped texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the highest points of adjacent spires in the first pyramid-shaped texture structure; or When the first surface corresponding to the first doping region has a first tower base-shaped texture structure, and the first tower base-shaped texture structure includes multiple first tower bases, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the geometric centers of adjacent first tower bases in the first tower base-shaped texture structure.

12. A photovoltaic module, wherein: The invention comprises the solar cell according to any one of claims 1 to 8, or the solar cell prepared by the preparation method according to any one of claims 9 to 11.

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