Solar cell and photovoltaic module

Abstract

The invention provides a solar cell and a photovoltaic module, and belongs to the technical field of semiconductors. The solar cell includes: a silicon substrate including a surface having a conductive region; the doped semiconductor layer is located on the conductive region of the silicon substrate, and the doped semiconductor layer comprises an electrode region; the passivation anti-reflection layer is located on the surface, away from the silicon substrate, of the doped semiconductor layer; the electrode is located on the passivation anti-reflection layer, and the electrode penetrates through the passivation anti-reflection layer and makes contact with the part of the electrode area; wherein the passivation anti-reflection layer at the edge of the electrode region is provided with a first corrosion region, and the first corrosion region is provided with a plurality of first holes.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to solar cells and photovoltaic modules. Background Art

[0002] With the development of solar cell technology, the life and reliability of solar cells are becoming more and more concerned. The life and reliability of solar cells are affected by many factors, among which the reasonable electrode structure is an important factor affecting the reliability.

[0003] However, the current design optimization of electrodes mainly focuses on improving the contact and passivation effect between electrodes and semiconductors, and there are relatively few technical solutions to improve battery reliability by optimizing the structure of electrodes. Summary of the invention

[0004] In view of this, in order to at least partially solve at least one of the above-mentioned technical problems, the present application provides a solar cell.

[0005] According to an embodiment of the present application, a solar cell is provided, comprising: a silicon substrate comprising a surface having a conductive region; a doped semiconductor layer located on the conductive region of the silicon substrate, the doped semiconductor layer comprising an electrode region; a passivation anti-reflection layer located on a surface of the doped semiconductor layer away from the silicon substrate; an electrode located on the passivation anti-reflection layer, the electrode passing through the passivation anti-reflection layer and contacting a portion of the electrode region; wherein the passivation anti-reflection layer located at the edge of the electrode region has a first corrosion region, and the first corrosion region has a plurality of first holes.

[0006] According to an embodiment of the present application, the electrode region includes a transition region without holes, and the transition region is located on a side of the first corrosion region away from an edge of the electrode region.

[0007] According to an embodiment of the present application, at least part of the plurality of first holes are blind holes, and / or the distribution density of the blind holes is greater than or equal to 50%.

[0008] According to an embodiment of the present application, the electrode region includes a second corrosion region, the second corrosion region is located in the middle of the electrode region, and the second corrosion region has a plurality of second holes.

[0009] According to an embodiment of the present application, the diameter of the second hole is larger than the diameter of the first hole.

[0010] According to an embodiment of the present application, the conductive region includes an N region and a P region, which are respectively located on the same surface or different surfaces of the solar cell; the doped semiconductor layer includes an N-type doped semiconductor layer and a P-type doped semiconductor layer, the N-type doped semiconductor layer is located on the N region, and the P-type doped semiconductor layer is located on the P region; the electrode region of the N-type doped semiconductor layer is the first electrode region, and the electrode region of the P-type doped semiconductor layer is the second electrode region, and the area ratio of the second hole located in the first electrode region on the first electrode region is smaller than the area ratio of the second hole located in the second electrode region on the second electrode region.

[0011] According to an embodiment of the present application, the area ratio of the second hole located in the first electrode region on the first electrode region is 0%~60%, and the area ratio of the second hole located in the second electrode region on the second electrode region is 10%~90%; and / or, the difference between the area ratio of the second hole located in the first electrode region on the first electrode region and the area ratio of the second hole located in the second electrode region on the second electrode region ranges from 10% to 30%.

[0012] According to an embodiment of the present application, the conductive region includes an N region and a P region, which are respectively located on the same surface or different surfaces of the solar cell; the passivation anti-reflection layer includes a first passivation anti-reflection layer and a second passivation anti-reflection layer, the first passivation anti-reflection layer is located on the doped semiconductor layer in the N region, and the second passivation anti-reflection layer is located on the doped semiconductor layer in the P region; the first corrosion region is strip-shaped and extends along the extension direction of the electrode region; along the extension direction perpendicular to the electrode region, the width of the first corrosion region located in the first passivation anti-reflection layer is different from the width of the first corrosion region located in the second passivation anti-reflection layer.

[0013] According to an embodiment of the present application, the width of the first corrosion region located in the first passivation anti-reflection layer is greater than the width of the first corrosion region located in the second passivation anti-reflection layer.

[0014] According to an embodiment of the present application, the conductive region includes an N region and a P region, which are respectively located on the same surface or different surfaces of the solar cell; the passivation anti-reflection layer includes a first passivation anti-reflection layer and a second passivation anti-reflection layer, the first passivation anti-reflection layer is located on the doped semiconductor layer in the N region, and the second passivation anti-reflection layer is located on the doped semiconductor layer in the P region; the distribution density of the first holes in the first corrosion zone of the first passivation anti-reflection layer is greater than the distribution density of the first holes in the first corrosion zone of the second passivation anti-reflection layer.

[0015] According to an embodiment of the present application, the conductive region includes an N region and a P region, which are respectively located on the same surface or different surfaces of the solar cell; the doped semiconductor layer includes an N-type doped semiconductor layer and a P-type doped semiconductor layer, the N-type doped semiconductor layer is located on the N region, and the P-type doped semiconductor layer is located on the P region; the electrode region of the N-type doped semiconductor layer is the first electrode region, and the electrode region of the P-type doped semiconductor layer is the second electrode region, and the width of the first electrode region is smaller than the width of the second electrode region.

[0016] According to an embodiment of the present application, a photovoltaic assembly is provided, comprising: a battery string, the battery string comprising the solar cells as described above; and a plurality of welding ribbons, the welding ribbons connecting at least two adjacent solar cells.

[0017] According to an embodiment of the present application, by providing a first corrosion area having a plurality of first holes on the passivation anti-reflection layer located at the edge of the electrode area, the contact area between the electrode and the passivation anti-reflection layer is increased to improve the adhesion of the electrode to the passivation anti-reflection layer, thereby improving the tensile strength of the electrode and improving the battery reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present application will become more apparent through the following description of the embodiments of the present application with reference to the accompanying drawings, in which:

[0019] Figure 1 is a schematic diagram of a partial structure of a solar cell according to an embodiment of the present application;

[0020] Figure 2 is a schematic structural diagram of a solar cell according to an embodiment of the present application after the electrodes are removed and pickled to expose the first corrosion zone and the transition zone;

[0021] Figure 3 is a SEM characterization image of the electrode area of ​​the solar cell of the embodiment of the present application after the electrode is removed and pickled;

[0022] Figure 4 is a schematic diagram of the overall structure of a back contact battery of an exemplary embodiment of the present application;

[0023] Figure 5 is a schematic diagram of the overall structure of a back contact battery of another exemplary embodiment of the present application;

[0024] Figure 6 It is a schematic diagram of the overall structure of a double-sided battery of an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0026] In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present application. However, it is apparent that one or more embodiments may be implemented without these specific details. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concepts of the present application.

[0027] The terms used herein are only for describing specific embodiments and are not intended to limit the present application. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0028] In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0029] The relative position between two components (such as film layers or regions) mentioned in this application, such as "above", "upper" or "above", may refer to the direct contact between the two components, or may refer to the indirect contact between the two components. Similarly, the relative position between two components mentioned in this application, such as "below", "lower" or "below", may refer to the direct contact between the two components, or may refer to the indirect contact between the two components. For example, when one of the components (such as film layers or regions) is referred to as "on another component", it can be directly on the other component, or there may be other components between the two. On the other hand, when a component is referred to as "directly on another component", there is no component between the two. In addition, when one of the components is referred to as "on another component", the two have an up-and-down relationship in the top-view direction, and this component can be above or below the other component, so this up-and-down relationship depends on the orientation of the device.

[0030] Reasonable electrode structure has a direct impact on the life and reliability of solar cells. However, in the related structures of solar cell electrodes, the main research focuses on improving the contact between the electrode and the semiconductor layer and the passivation effect, while less research is done on how to optimize the related structure of the electrode to improve battery reliability.

[0031] In the process of realizing the concept of this application, it was found that by selecting a suitable preparation process to control the edge structure of the electrode and forming a porous structure on the passivation anti-reflection layer located at the edge of the electrode area of ​​the doped semiconductor layer, the adhesion of the electrode can be improved by increasing the contact area between the electrode edge and the passivation anti-reflection layer, thereby improving the battery reliability.

[0032] Specifically, according to an embodiment of one aspect of the present application, a solar cell is provided. Figure 1 is a schematic diagram of a partial structure of a solar cell according to an embodiment of the present application. Figure 1 As shown, the solar cell provided by the embodiment of the present application includes a silicon substrate 1, a doped semiconductor layer 2, a passivation anti-reflection layer 3 and an electrode 4, wherein: the silicon substrate 1 includes a surface having a conductive area 11; the doped semiconductor layer 2 is located on the conductive area 11 of the silicon substrate 1, and the doped semiconductor layer 2 includes an electrode area 21, such as the portion indicated by the dotted line frame; the passivation anti-reflection layer 3 is located on the surface of the doped semiconductor layer 2 away from the silicon substrate 1; the electrode 4 is located on the passivation anti-reflection layer 3, and the electrode 4 passes through the passivation anti-reflection layer 3 and contacts a portion of the electrode area 21.

[0033] According to an embodiment of the present application, the silicon substrate 1 may be an N-type silicon substrate or a P-type silicon substrate. Specifically, the silicon substrate 1 may be, for example, a semiconductor material selected from monocrystalline silicon, polycrystalline silicon, and microcrystalline silicon, preferably an N-type or P-type monocrystalline silicon substrate. The conversion efficiency of cells based on monocrystalline silicon substrates is higher than that of other types such as polycrystalline silicon cells. By introducing donor impurities such as group VA elements such as phosphorus (P), arsenic (As) or antimony (Sb) into these semiconductor materials, an N-type silicon substrate is obtained, or by introducing acceptor impurities such as group IIIA elements such as boron (B), aluminum (Al) or gallium (Ga) into these semiconductor materials, a P-type silicon substrate is obtained. Here, there are no excessive restrictions on the specific type of the silicon substrate 1. In practical applications, technicians can select a suitable silicon substrate 1 as needed.

[0034] According to the embodiment of the present application, the surface of the silicon substrate 1 can be the front and / or back of the battery, without limitation. Generally speaking, the front of the battery is used as the light-receiving surface, and the back is used as the backlight surface, or it can also be double-sided, in which case both the front and back are used as light-receiving surfaces. The surface of the silicon substrate 1 having the conductive area can be a polished surface, and tower base structures can be discretely distributed, so as to be suitable for obtaining a relatively flat passivation anti-reflection layer 3 on the polished surface, so as to facilitate the formation of a first corrosion area 31 having a plurality of first holes 32.

[0035] The conductive region 11 on the surface of the silicon substrate 1 is a region suitable for separating and / or transmitting carriers, and further, the surface region of the silicon substrate 1 formed with a doped semiconductor layer can be used as the conductive region. Further optionally, according to different conductivity types, the conductive region 11 can include an N region and / or a P region, and the N region and the P region can be located on the same surface or different surfaces of the solar cell, wherein, when the two are located on the same surface, the N region and the P region can be partial regions of one surface of the silicon substrate 1, and when the two are located on different surfaces, the N region and the P region can be at least partial regions of one surface of the silicon substrate 1, that is, they can be an entire surface of the silicon substrate 1, or partial regions of the surface of the silicon substrate 1.

[0036] According to an embodiment of the present application, the doped semiconductor layer 2 may include, for example, semiconductor materials such as single crystal silicon, polycrystalline silicon or microcrystalline silicon, and its doping type may be N-type doping and / or P-type doping. For example, donor impurities such as phosphorus (P), arsenic (As) or antimony (Sb) and other VA group elements may be introduced into the semiconductor material to achieve N-type doping; or acceptor impurities such as boron (B), aluminum (Al) or gallium (Ga) and other IIIA group elements may be introduced into the aforementioned semiconductor material to achieve P-type doping. The electrode region 21 of the doped semiconductor layer 2 represents an area that can be used to form an electrode, so that the electrode can contact the doped semiconductor layer 2 in the area. This is in consideration of the accuracy of the electrode manufacturing process, so the electrode region 21 includes an area where the electrode position can be reasonably adjusted.

[0037] According to the embodiment of the present application, the passivation anti-reflection layer 3 can be a single layer film formed by silicon dioxide, aluminum dioxide, silicon nitride or silicon oxynitride, or a laminated film composed of one or more of the above materials. It can take into account the protection and passivation of the underlying silicon substrate 1 or functional layer, such as the doped semiconductor layer 2, and play an anti-reflection role on the light incident on the surface of the silicon substrate 1. It can be prepared by plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD) or atomic layer deposition (ALD), so as to form a relatively dense passivation anti-reflection layer 3.

[0038] According to an embodiment of the present application, the material of the electrode 4 may be silver, silver-coated copper, aluminum or copper, etc., and the preferred electrode types include silver electrodes, doped aluminum electrodes (doped elements are group IIIA elements) or silver aluminum electrodes. The electrode 4 may be made by printing a suitable electrode slurry, and then sequentially dried, sintered and light-injected. The printing method may be, for example, screen printing or inkjet printing, and may further be a low-cost screen printing method. The electrode may include structures such as collector grid lines, bus grid lines or pads.

[0039] According to the embodiment of the present application, the passivation anti-reflection layer 3 located at the edge of the electrode region 21 has a first corrosion region 31, and the first corrosion region 31 has a plurality of first holes 32. The present application selects a suitable preparation process to make the passivation anti-reflection layer and the electrode, so that after the electrode is sintered, a first corrosion region suitable for contacting the electrode can be formed on the passivation anti-reflection layer located at the edge of the electrode region, and the porous structure of the first corrosion region can increase the contact area between the electrode edge and the passivation anti-reflection layer, thereby improving the adhesion of the electrode to improve the battery reliability.

[0040] According to an embodiment of the present application, at least part of the plurality of first holes 32 are blind holes, which are suitable for accommodating metal crystals or glass bodies formed after sintering the electrode 4, and are used to improve the tensile strength of the electrode 4, wherein the metal crystals are alloys of metal elements and silicon elements containing the electrode, such as silver-silicon alloys, etc. Further optionally, the distribution density of the blind holes is 1 to 40 per μm. 2 , for example, it can be 1 / μm 2 , 5 / μm 2 , 8 / μm 2 , 10 / μm 2 , 15 / μm 2 , 18 / μm 2 , 20 / μm 2 , 25 / μm 2 , 30 / μm 2 , 35 / μm 2 , 40 / μm 2 Too few blind holes are not conducive to improving the adhesion of the electrode 4 on the passivation anti-reflection layer 3. The "distribution density" in this application may refer to the number of characterization objects such as blind holes in a characterization area per unit area such as the first corrosion area.

[0041] The present application does not impose any restrictions on the measurement of the distribution density of blind holes. Those skilled in the art can measure the density by conventional methods in the art. For example, a scanning electron microscope (SEM) can be used to collect images of the surface of the battery cell after the electrodes are removed and pickled. On the measured SEM top view, at least one area of ​​the same size, for example, 1 μm 2 The number of blind holes observed in each area is counted, and then the number of blind holes per unit area in each area is calculated and the average value is taken, which is the distribution density of the blind holes. It should be noted that in order to reduce the influence of image acquisition resolution and statistical errors, when measuring the aperture and distribution density of blind holes, blind holes with an aperture less than 20nm are not included in the measurement range.

[0042] According to an embodiment of the present application, further optionally, when the doped semiconductor layer 2 is an N-type doped semiconductor layer or a P-type doped semiconductor layer, the aperture and distribution of the first holes 32 on the first corrosion area 31 are different.

[0043] Exemplarily, the passivation anti-reflection layer located on the N-type doped semiconductor layer is the first passivation anti-reflection layer, and the passivation anti-reflection layer located on the P-type doped semiconductor layer is the second passivation anti-reflection layer. The aperture of the first hole located in the first passivation anti-reflection layer is 20-300 nm, for example, it can be 20 nm, 50 nm, 80 nm, 100 nm, 130 nm, 150 nm, 180 nm, 200 nm, 130 nm, 150 nm, 180 nm, 200 nm, 230 nm, 250 nm, 280 nm, 300 nm, etc., and the aperture of the first hole located in the second passivation anti-reflection layer is 40-400 nm, for example, it can be 40 nm, 50 nm, 80 nm, 100 nm, 130 nm, 150 nm, 180 nm, 200 nm, 230 nm, 250 nm, 280 nm, 300 nm, 330 nm, 350 nm, 380 nm, 400 nm nm, etc.

[0044] For example, the distribution density of the first holes in the first corrosion area of ​​the first passivation anti-reflection layer is 10-40 holes / μm. 2 , for example, it can be 10 / μm 2 , 15 / μm 2 , 20 / μm 2 , 25 / μm 2 , 30 / μm 2 , 35 / μm 2 , 40 / μm 2 etc.; the distribution density of the first holes in the first corrosion area of ​​the second passivation anti-reflection layer is 1-20 / μm 2 , for example, it can be 1 / μm 2 , 5 / μm 2 , 8 / μm 2 , 10 / μm 2 , 15 / μm 2 , 18 / μm 2 , 20 / μm 2 wait.

[0045] Exemplarily, the width of the first corrosion zone located in the first passivation anti-reflection layer is 0.2~4μm, for example, it can be 0.2μm, 0.5μm, 0.8μm, 1.0μm, 1.2μm, 1.5μm, 1.8μm, 2.0μm, 2.3μm, 2.5μm, 2.8μm, 3.0μm, 3.3μm, 3.5μm, 3.8μm, 4.0μm, etc., and the width of the first corrosion zone located in the second passivation anti-reflection layer is 0.1~2μm, for example, it can be 0.1μm, 0.3μm, 0.5μm, 0.8μm, 1.0μm, 1.2μm, 1.5μm, 1.8μm, 2.0μm, etc.

[0046] Among them, this application does not impose any restrictions on the measurement of the aperture of the first hole, and those skilled in the art can measure it by conventional methods in the art. For example, a scanning electron microscope (SEM) can be used to capture images of the surface of the battery cell after the electrode is removed and pickled. The apertures of the holes observed in the measured SEM top view are statistically analyzed. The maximum diagonal dimension of the first hole in a certain direction can be used as the aperture, or the diameter of an equivalent circle with the same area as the first hole can be used as the aperture, which is conducive to simplifying the measurement and statistical analysis.

[0047] The present application does not impose any limitation on the measurement of the distribution density of the first holes. A person skilled in the art can measure the distribution density of the first holes by conventional methods in the art. For example, at least one hole with the same area size, for example, 1 μm, can be taken from the above SEM top view. 2 The number of first holes observed in each area is counted, and then the number of first holes per unit area in each area is calculated and the average value is taken, which is the distribution density of the first holes. It should be noted that in order to reduce the influence of image acquisition resolution and statistical errors, when measuring the pore size and distribution density of the first holes, the first holes with a pore size less than 20nm are not included in the measurement range.

[0048] This application does not impose any restrictions on the measurement of the width of the first corrosion zone. Those skilled in the art can measure it by conventional methods in the art. For example, on the above-mentioned SEM top view, an area within a certain length range, such as 10 μm, can be taken in the extension direction of the first corrosion zone, and the average value of the width of the first corrosion zone within the length range can be calculated.

[0049] In this way, the passivation anti-reflection layer located on the N-type doped semiconductor layer is set to have a porous structure with fine and / or dense holes, and can be further matched with a first corrosion zone with a larger width, which can significantly improve the reliability of the electrode located on the N-type doped semiconductor layer. Alternatively, the passivation anti-reflection layer located on the P-type doped semiconductor layer is set to have a porous structure with coarse and / or sparse holes, and can be further matched with a first corrosion zone with a smaller width. While improving the reliability of the electrode located on the P-type doped semiconductor layer, it is beneficial to reduce the damage to the passivation anti-reflection layer at the edge of the electrode area and reduce the recombination loss. Especially for N-type silicon substrates with higher minority carrier lifetimes, the PN junction region involves the injection and recombination of minority carriers. At this time, reducing the junction region recombination loss is more beneficial to improving the photoelectric conversion efficiency.

[0050] According to an embodiment of the present application, Figure 2 FIG. 1 is a schematic diagram of the structure of a solar cell according to an embodiment of the present application after removing the electrode and pickling to expose the first corrosion zone and the transition zone, wherein the dotted line box indicates the electrode zone 21. Figure 2 As shown, the electrode region 21 includes a transition region 211 without holes, and the transition region 211 is located on the side of the first corrosion region 31 away from the edge of the electrode region 21. The transition region 211 can disperse the contact stress of the electrode 4 between the doped semiconductor layer 2 and the passivation anti-reflection layer 3, thereby improving the connection reliability of the electrode.

[0051] According to the embodiment of the present application, the passivation anti-reflection layer 3 at the two side edges of the electrode region 21 has a first corrosion region 31, and a transition region 211 is provided at the two first corrosion regions 31 on the side away from the edge of the electrode region 21. This can improve the contact stress balance of the electrode 4 and improve the connection reliability of the electrode 4.

[0052] In order to better illustrate the morphology of the electrode area, this application uses NHNO 3 -HF-HNO 3 The solution is used to acid-wash the solar cell, exposing the doped semiconductor layer 2 and the passivation anti-reflection layer 3 . Figure 3 2 is a SEM characterization image of the electrode area of ​​the solar cell of the embodiment of the present application after the electrode is removed and pickled, wherein the dotted line marks the boundary between part of the transition area 211 and the first corrosion area 31. Figure 2 and Figure 3 As shown, it can be seen that a transition zone 211 is provided on one side of the first corrosion zone 31 away from the edge of the electrode zone 21. The transition zone 211 is a zone without holes. It is speculated that its formation is related to factors such as the wetting angle of the electrode slurry, the distribution of glass material and the sintering shrinkage during the production of the solar cell. It should be noted that the zone without holes here refers to a zone where it is difficult to observe obvious holes, for example, a zone where the pore diameter is less than 20nm.

[0053] According to an embodiment of the present application, at least a portion of the transition zone 211 may be covered or uncovered with the passivation anti-reflection layer 3 . Obviously, the covered passivation anti-reflection layer 3 has no holes or it is difficult to observe obvious holes.

[0054] Exemplarily, the width of the transition region 211 accounts for 0% to 35% of the width of the electrode region, for example, 0%, 5%, 10%, 15%, 20%, 25%, 30%, etc. If the width of the transition region 211 is too large, the contact space between the electrode 4 and the passivation anti-reflection layer 3 and the doped semiconductor layer 2 will be small, resulting in a decrease in the tensile strength of the electrode.

[0055] According to the embodiments of the present application, Figure 1 , Figure 2 , Figure 3 As shown, the electrode region 21 may further include a second corrosion region 212, which is located in the middle of the electrode region 21, and has a plurality of second holes 22. The second holes 22 are suitable for accommodating metal crystals or glass bodies formed after the electrode 4 is sintered, and are used to improve the tensile strength of the electrode 4. At the same time, since the contact area between the electrode 4 and the doped semiconductor layer 2 is increased, it is helpful to improve the contact performance between the electrode 4 and the doped semiconductor layer 2.

[0056] According to the embodiment of the present application, the aperture of the second hole 22 is larger than the aperture of the first hole 32. Here, the average aperture of the second hole 22 may be larger than the average aperture of the first hole 32; or, a certain number ratio (for example, more than 50%, preferably more than 70%, and more preferably more than 90%) of the aperture of the second hole 22 may be larger than the maximum aperture of the first hole 32. In this way, the larger aperture of the second hole 22 is conducive to increasing the contact area between the electrode 4 and the doped semiconductor layer 2, thereby improving the adhesion of the electrode to improve the electrode connection reliability, and improving the contact resistance to improve the carrier collection ability and improve the battery efficiency; while the aperture of the first hole 32 is relatively small, while ensuring the adhesion of the electrode 4 on the passivation anti-reflection layer 3, it can ensure the structural strength of the passivation anti-reflection layer located at the edge of the electrode area, thereby improving the connection reliability of the electrode 4.

[0057] According to the embodiment of the present application, when the doped semiconductor layer 2 is an N-type doped semiconductor layer or a P-type doped semiconductor layer, the aperture and distribution of the second holes 22 on the second corrosion area 212 are different.

[0058] Exemplarily, the electrode region of the N-type doped semiconductor layer is the first electrode region, and the electrode region of the P-type doped semiconductor layer is the second electrode region. The area ratio of the second hole located in the first electrode region on the first electrode region is 0-60%, such as 0%, 10%, 20%, 30%, 40%, 50%, 60%, etc.; or, the area ratio of the second hole located in the second electrode region on the second electrode region is 10%-90%, such as 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, etc. The appropriate area ratio of the second hole can take into account the balance between contact performance and passivation effect.

[0059] The present application does not impose any limitation on the measurement of the area ratio of the second holes, and those skilled in the art can measure it by conventional methods in the art, for example, by taking at least one of the same area size, for example, 4 μm, on the above SEM top view. 2 The area ratio of the second holes observed in each area is calculated, and then the average area ratio of the second holes in at least one area is calculated, which is the area ratio of the second holes.

[0060] According to an embodiment of the present application, the passivation anti-reflection layer 3 of the present application may also include an ablation affected area 33, which is located on the side of the first corrosion area 31 close to the edge of the electrode area 21. It is mainly an area affected by the sintering and light injection process of the electrode 4, which is manifested as changes in the surface morphology or microstructure of the material.

[0061] According to an embodiment of the present application, the contact structure located at the edge of the electrode region of the present application is applicable to different types of solar cells, for example, a bifacial cell or a back contact cell. Figure 4 is a schematic diagram of the overall structure of a back contact battery of an exemplary embodiment of the present application; Figure 5 is a schematic diagram of the overall structure of a back contact battery of another exemplary embodiment of the present application; Figure 6 Schematic diagram of the overall structure of a bifacial battery according to an exemplary embodiment of the present application. Figure 4 and Figure 5 As shown, the conductive region 11 includes an N region 111 and a P region 112, and the N region 111 and the P region 112 are respectively located on the same surface of the solar cell, thereby forming a back contact cell; or as shown in FIG. Figure 6 As shown, the N region 111 and the P region 112 are respectively located on different surfaces of the solar cell, that is, two surfaces arranged opposite to each other, so as to form a bifacial cell.

[0062] In one embodiment, the contact structure located at the edge of the electrode region of the present application is applicable to one of the N region 111 and the P region 112 , and the doped semiconductor layer 2 can be an N-type doped semiconductor layer or a P-type doped semiconductor layer.

[0063] For example, Figure 1 and Figure 4 As shown, taking the HPBC (Hybrid Passivated Back Contact) cell as an example, the silicon substrate 1 includes a first surface and a second surface opposite to each other, and the conductive region 11 of the silicon substrate 1 includes an N region 111 and a P region 112 that are alternately distributed. The tunneling oxide passivation contact structure can be located in the N region, and the passivation emitter structure can be located in the P region. At this time, there is no electrode structure on the second surface of the silicon substrate 1, which can help reduce the shading of the front electrode and thus improve the light utilization rate. The second surface of the silicon substrate 1 can be a velvet structure (not shown in the figure).

[0064] Further, the passivated emitter structure includes a doped conductive layer 202 located in the P region 112 of the silicon substrate 1, and a third passivated anti-reflection layer 302 located on the doped conductive layer 202. Exemplarily, an aluminum-containing electrode can be manufactured after the third passivated anti-reflection layer 302 is grooved, and the silicon substrate in the P region 112 is P-doped using the aluminum-containing electrode to obtain the doped conductive layer 202 on the P region 112.

[0065] The N-type doped semiconductor layer 201 is located on the N region 111, and its material can be polycrystalline silicon or microcrystalline silicon. At this time, the first passivation anti-reflection layer 301 located at the edge of the electrode region 21 of the N-type doped semiconductor layer 201 has a first corrosion region 31 for contacting the electrode 4. Further, the electrode region 21 also includes a transition region 211 located on the side of the first corrosion region 31 away from the electrode region edge and a second corrosion region 212 located in the middle of the electrode region 21. The specific structures and morphologies of the first corrosion region 31, the transition region 211 and the second corrosion region 212 are not described in detail.

[0066] At this time, the N-type doped semiconductor layer 201 can be prepared by low temperature chemical vapor deposition (LPCVD), and the thickness can be 100~600nm, for example, it can be 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, etc.

[0067] Further optionally, the solar cell may also include an interface passivation layer 5, located between the N-type doped semiconductor layer 201 and the silicon substrate 1, for selectively passing through the majority carriers to achieve field passivation effect, and improve the carrier separation and collection effect. The interface passivation layer 5 may be aluminum oxide, silicon oxide, titanium oxide, etc., and may form a tunneling oxidation passivation contact structure with the N-type doped semiconductor layer 201. The interface passivation layer 5 of the aforementioned material also has the function of blocking the electrode 4 from corroding the silicon substrate 1 inwardly. At this time, the interface passivation layer 5 may be prepared by low temperature chemical vapor deposition (LPCVD), and the thickness may be 0.5~10nm, for example, 0.5 nm, 1 nm, 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, etc.

[0068] In another embodiment, the contact structure located at the edge of the electrode region of the present application can also be applied to both the N region 111 and the P region 112 .

[0069] For example, taking a back contact battery as an example, Figure 1 and Figure 5 As shown, taking a TBC (TopCon-Back Contact, tunneling oxide passivation contact back contact) battery as an example, the silicon substrate 1 includes a first surface and a second surface opposite to each other, and the N region and the P region can be alternately distributed on the first surface. The doped semiconductor layer 2 may include an N-type doped semiconductor layer 201 and a P-type doped semiconductor layer 203, the N-type doped semiconductor layer 201 is located on the N region 111, and the P-type doped semiconductor layer 203 is located on the P region 112.

[0070] For example Figure 5 As shown, the TBC battery may also include a first interface passivation layer 501 and a second interface passivation layer 502. Tunneling oxide passivation contact structures are formed between the first interface passivation layer 501 and the N-type doped semiconductor layer 201, and between the second interface passivation layer 502 and the P-type doped semiconductor layer 203. One of the two tunneling oxide passivation contact structures is a PN junction, and the other is a high-low junction. The two can be further isolated by an isolation region (i.e., an isolation region). The isolation region can be, for example, an isolation trench located between the N region and the P region.

[0071] In the embodiment of the present application, the passivation anti-reflection layer 3 may include a first passivation anti-reflection layer 301 and a second passivation anti-reflection layer 303. The first passivation anti-reflection layer 301 is located on the N-type doped semiconductor layer 201, and the second passivation anti-reflection layer 303 is located on the P-type doped semiconductor layer 203. At this time, the electrode region of the N-type doped semiconductor layer 201 is the first electrode region, and the electrode region of the P-type doped semiconductor layer 203 is the second electrode region. The first passivation anti-reflection layer 301 located at the edge of the first electrode region and the second passivation anti-reflection layer 303 located at the edge of the second electrode region respectively have a first corrosion region 31. Further, the first electrode region and the second electrode region may also include a transition region 211 and a second corrosion region 212, respectively. The structures of the first corrosion region 31, the transition region 211 and the second corrosion region 212 are the same as those described above and will not be described in detail.

[0072] In the embodiment of the present application, the aperture of the first hole 32 located in the first passivation anti-reflection layer 301 is smaller than the aperture of the first hole 32 located in the second passivation anti-reflection layer 303. Here, the average aperture of the first hole located in the first passivation anti-reflection layer 301 may be smaller than the average aperture of the first hole located in the second passivation anti-reflection layer 303; or, a certain number ratio (for example, more than 50%, preferably more than 70%, more preferably more than 90%) of the aperture of the first hole 32 located in the first passivation anti-reflection layer 301 may be smaller than the minimum aperture of the first hole 32 located in the second passivation anti-reflection layer 303. Exemplarily, the difference between the two may further be 20-100 nm, for example, 20 nm, 30 nm, 45 nm, 50 nm, 75 nm, 80 nm, 95 nm, 100 nm, etc.

[0073] In the embodiment of the present application, the distribution density of the first holes on the first corrosion area of ​​the first passivation anti-reflection layer 301 is greater than the distribution density of the first holes on the first corrosion area of ​​the second passivation anti-reflection layer 303. For example, the difference between the two can be further selected as 9 to 20 holes / μm. 2 , for example, it can be 9 / μm 2 , 12 / μm 2 , 14 / μm 2 , 16 / μm 2 , 18 / μm 2 , 20 / μm 2 wait.

[0074] Thus, by adjusting the aperture and distribution density of the first holes on the first corrosion zone on the first passivation anti-reflection layer 301 and the second passivation anti-reflection layer 303 within the above relationship range, even if the width of the first corrosion zone on the P zone is appropriately reduced, it is also beneficial to improve the tensile strength of the N zone and P zone electrodes simultaneously. In addition, if the width of the first corrosion zone on the P zone is reduced, it is beneficial to reduce the recombination loss, thereby further improving the photoelectric conversion efficiency of the battery.

[0075] In the embodiment of the present application, the silicon substrate 1 includes a first surface and a second surface opposite to each other, and the N region and the P region may be alternately distributed on the first surface, and the surface of the N region is lower than the surface of the P region ( Figure 5 ), and thus the upper surface of the N-region electrode is lower than the upper surface of the P-region electrode. Therefore, during the welding process of the cell and the welding strip, the tensile force borne by the N-region electrode in the direction along the thickness of the solar cell is greater than the tensile force borne by the P-region electrode in the same direction. In this way, by adjusting the aperture and distribution density of the first holes on the first corrosion area on the first passivation anti-reflection layer 301 and the second passivation anti-reflection layer 303 within the above relationship range, that is, the distribution of the first holes in the N-region is small and / or dense, so that the distribution of the first holes in the N-region provides a greater adhesion between the electrode and the solar cell than the distribution of the first holes in the P-region provides a greater adhesion between the electrode and the solar cell, which is conducive to balancing the tensile resistance between the P-region and N-region electrodes.

[0076] In an embodiment of the present application, the first corrosion zone 31 is strip-shaped and extends along the extension direction of the electrode zone; along the extension direction perpendicular to the electrode zone, the width of the first corrosion zone located in the first passivation anti-reflection layer 301 is different from the width of the first corrosion zone located in the second passivation anti-reflection layer 303.

[0077] In order to reduce the P-zone recombination loss, the width of the first corrosion zone located in the first passivation anti-reflection layer 301 can be greater than the width of the first corrosion zone located in the second passivation anti-reflection layer 303. By way of example, the difference between the two can be further selected as 0.1~2μm, for example, it can be 0.1μm, 0.2μm, 0.4μm, 0.6μm, 0.8μm, 1.0μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm, 2.0μm, etc.

[0078] In order to eliminate the contact difference caused by the lower doping concentration of the P-type doped semiconductor layer compared to the N-type doped semiconductor layer, the width of the first electrode region is smaller than the width of the second electrode region, so as to reduce the contact resistance between the P-type doped semiconductor layer and the electrode, improve the carrier collection balance between the N region and the P region, and improve the battery efficiency. Exemplarily, the width of the first electrode region can be 20~35μm, for example, it can be 20μm, 23μm, 25μm, 28μm, 30μm, 32μm, 35μm, etc.; the width of the second electrode region can be 25~40μm, for example, it can be 25μm, 28μm, 30μm, 32μm, 35μm, 38μm, 40μm, etc.; the difference between the two can be further selected as 5~15μm, for example, it can be 5μm, 8μm, 10μm, 12μm, 15μm, etc.

[0079] In an embodiment of the present application, the area ratio of the second hole located in the first electrode region on the first electrode region is smaller than the area ratio of the second hole located in the second electrode region on the second electrode region. Exemplarily, the difference between the two can be 10% to 30%. By adjusting the area ratio of the second hole located in the second electrode region to be larger, when the P-type doped semiconductor layer 203 has a lower doping concentration and a larger contact resistance than the N-type doped semiconductor layer 201, it is beneficial to further improve the contact performance between the P-type doped semiconductor layer 203 and the P-region electrode, thereby facilitating the balance of carrier transport between the N-region and the P-region.

[0080] Of course, the solar cell of the present application is not limited to the above-mentioned TBC cell, and the solar cell of the present application can also be a TOPCon cell, such as Figure 1 and Figure 6 As shown, a TOPCon battery with a tunneling oxide passivation contact structure on one side is shown. The main difference from the TBC battery is that the N region 111 is located on the first surface of the silicon substrate 1, the P region 112 is located on the second surface of the silicon substrate 1, the tunneling oxide passivation contact structure is located in the N region 111, and the passivated emitter structure is located in the P region 112.

[0081] The tunneling oxide passivation contact structure includes an N-type doped semiconductor layer 201 located in the N region 111, and the material of the N-type doped semiconductor layer 201 may be polycrystalline silicon or microcrystalline silicon; and a first passivation anti-reflection layer 301 located on the N-type doped semiconductor layer 201. The passivation emitter structure includes a P-type doped semiconductor layer 203 located in the P region 112, and a second passivation anti-reflection layer 303 located on the P-type doped semiconductor layer 203. The P-type doped semiconductor layer 203 may be obtained on the P region 112 by performing internal diffusion doping through a boron diffusion process in the P region 112.

[0082] Of course, it is not limited to this, and can also be used as Figure 6The passivated emitter structure shown in the P region 112 is replaced by another tunneling oxide passivation contact structure, specifically including a P-type doped semiconductor layer 203 located on the P region 112, whose material may be polycrystalline silicon or microcrystalline silicon, etc., and another interface passivation layer located on the P-type doped semiconductor layer 203. The corresponding solar cell is a TOPCon cell having a tunneling oxide passivation contact structure on both sides.

[0083] At this time, the electrode region of the N-type doped semiconductor layer 201 is also used as the first electrode region, and the electrode region of the P-type doped semiconductor layer 203 is used as the second electrode region. The first passivation anti-reflection layer 301 located at the edge of the first electrode region and the second passivation anti-reflection layer 303 located at the edge of the second electrode region respectively have a first corrosion region 31. In the embodiment of the present application, the first electrode region and the second electrode region may respectively include a transition region 211 and a second corrosion region 212. The structures of the first corrosion region 31, the transition region 211 and the second corrosion region 212 are the same as those described above and are not described in detail.

[0084] In an embodiment of the present application, a photovoltaic module is provided, including a battery string, the battery string including the above-mentioned solar cell; a plurality of welding strips, the welding strips connecting at least two adjacent solar cells. By forming a first corrosion zone suitable for contacting the electrode on the passivation anti-reflection layer at the edge of the electrode area in the solar cell, the contact area between the electrode edge and the passivation anti-reflection layer can be increased based on the porous structure of the first corrosion zone, thereby improving the adhesion of the electrode. In the process of connecting the solar cell and the welding strip, the welding strip contacts the electrode, and the electrode has good adhesion, which means that the electrode has good tensile strength after being connected with the welding strip, so as to improve the reliability of the connection between the welding strip and the solar cell.

[0085] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A solar cell, characterized in that: include: a silicon substrate including a surface having a conductive region; A doped semiconductor layer, located on the conductive region of the silicon substrate, wherein the doped semiconductor layer includes an electrode region; A passivation anti-reflection layer is located on a surface of the doped semiconductor layer away from the silicon substrate; An electrode, located on the passivation anti-reflection layer, the electrode passes through the passivation anti-reflection layer and contacts a portion of the electrode region; The passivation anti-reflection layer located at the edge of the electrode region has a first corrosion region, and the first corrosion region has a plurality of first holes.

2. The solar cell according to claim 1, characterized in that The electrode region comprises a transition region without holes, and the transition region is located on a side of the first corrosion region away from an edge of the electrode region.

3. The solar cell according to claim 1, characterized in that At least some of the plurality of first holes are blind holes, and / or the distribution density of the blind holes is 1-40 / μm 2 .

4. The solar cell according to claim 1, characterized in that The electrode region includes a second corrosion region, the second corrosion region is located in the middle of the electrode region, and the second corrosion region has a plurality of second holes.

5. The solar cell according to claim 4, characterized in that: The diameter of the second hole is larger than that of the first hole.

6. The solar cell according to claim 4, characterized in that: The conductive region includes an N region and a P region, which are respectively located on the same surface or different surfaces of the solar cell; The doped semiconductor layer comprises an N-type doped semiconductor layer and a P-type doped semiconductor layer, the N-type doped semiconductor layer is located on the N region, and the P-type doped semiconductor layer is located on the P region; The electrode region of the N-type doped semiconductor layer is used as the first electrode region, and the electrode region of the P-type doped semiconductor layer is used as the second electrode region, and the area ratio of the second hole located in the first electrode region on the first electrode region is smaller than the area ratio of the second hole located in the second electrode region on the second electrode region.

7. The solar cell according to claim 6, characterized in that: The second hole located in the first electrode region accounts for 0% to 60% of the area of ​​the first electrode region, and the second hole located in the second electrode region accounts for 10% to 90% of the area of ​​the second electrode region; And / or, a difference between a proportion of an area of ​​the second hole located in the first electrode region on the first electrode region and a proportion of an area of ​​the second hole located in the second electrode region on the second electrode region is in a range of 10% to 30%.

8. The solar cell according to claim 1, characterized in that The conductive region includes an N region and a P region, which are respectively located on the same surface or different surfaces of the solar cell; The passivation anti-reflection layer comprises a first passivation anti-reflection layer and a second passivation anti-reflection layer, the first passivation anti-reflection layer is located on the doped semiconductor layer in the N region, and the second passivation anti-reflection layer is located on the doped semiconductor layer in the P region; the first corrosion region is strip-shaped and extends along the extension direction of the electrode region; Along an extension direction perpendicular to the electrode region, a width of a first corrosion region located in the first passivation anti-reflection layer is different from a width of a first corrosion region located in the second passivation anti-reflection layer.

9. The solar cell according to claim 8, characterized in that The width of the first etching region located in the first passivation anti-reflection layer is greater than the width of the first etching region located in the second passivation anti-reflection layer.

10. The solar cell according to claim 1, characterized in that: The conductive region includes an N region and a P region, which are respectively located on the same surface or different surfaces of the solar cell; The passivation anti-reflection layer comprises a first passivation anti-reflection layer and a second passivation anti-reflection layer, the first passivation anti-reflection layer is located on the doped semiconductor layer in the N region, and the second passivation anti-reflection layer is located on the doped semiconductor layer in the P region; The distribution density of the first holes located in the first corrosion region of the first passivation anti-reflection layer is greater than the distribution density of the first holes located in the first corrosion region of the second passivation anti-reflection layer.

11. The solar cell according to claim 1, characterized in that: The conductive region includes an N region and a P region, which are respectively located on the same surface or different surfaces of the solar cell; The doped semiconductor layer comprises an N-type doped semiconductor layer and a P-type doped semiconductor layer, the N-type doped semiconductor layer is located on the N region, and the P-type doped semiconductor layer is located on the P region; The electrode region of the N-type doped semiconductor layer is used as a first electrode region, and the electrode region of the P-type doped semiconductor layer is used as a second electrode region. The width of the first electrode region is smaller than the width of the second electrode region.

12. A photovoltaic module, characterized in that: include: A battery string, the battery string comprising the solar cell according to any one of claims 1 to 11; A plurality of welding strips, wherein the welding strips at least connect two adjacent solar cells.

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