Metal-semiconductor contact structure, solar cell and photovoltaic module

Abstract

The invention relates to the field of solar cells, and discloses a metal-semiconductor contact structure, a solar cell and a photovoltaic module. The metal-semiconductor contact structure comprises a doped silicon layer; the metal electrode is electrically connected with the doped silicon layer through a plurality of conductive structures; wherein a contact interface of the doped silicon layer and the metal electrode comprises a first contact area and a second contact area, and the number of the conductive structures in the second contact area is smaller than that of the conductive structures in the first contact area. According to the metal semiconductor contact structure, the passivation performance of the doped silicon layer can be improved while the contact effect of the metal electrode and the doped silicon layer is guaranteed.

Description

Gold-plated contact structure, solar cells, photovoltaic modules Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a gold-semiconductor contact structure, a solar cell, and a photovoltaic module. Background Technology

[0002] The gold-semiconductor contact structure is a crucial component of solar cells, and the interfacial contact between the metal electrode and the doped silicon layer plays a vital role in carrier transport. A good interfacial contact facilitates efficient carrier transport from the doped silicon layer to the metal electrode. However, this good contact often leads to excessive corrosion of the doped silicon layer, accelerated carrier recombination, and decreased passivation performance. Therefore, improving the passivation performance of the doped silicon layer while ensuring effective contact between the metal electrode and the doped silicon layer is a pressing issue that needs to be addressed. Summary of the Invention

[0003] This application discloses a gold-semiconductor contact structure, a solar cell, and a photovoltaic module. The gold-semiconductor contact structure of this application can maintain the excellent passivation performance of the doped silicon layer while ensuring the contact effect between the metal electrode and the doped silicon layer.

[0004] In a first aspect, this application discloses a gold-semiconductor contact structure, the gold-semiconductor contact structure comprising: a doped silicon layer; a metal electrode, wherein the metal electrode and the doped silicon layer are electrically connected through a plurality of conductive structures; wherein the contact interface between the doped silicon layer and the metal electrode comprises a first contact region and a second contact region, and the number of conductive structures in the second contact region is less than the number of conductive structures in the first contact region.

[0005] Furthermore, the ratio of the number of conductive structures in the first contact region to the number of conductive structures in the second contact region is M, where M satisfies: 1 < M ≤ 500.

[0006] Further, along the length direction of the first contact area, the first contact area and the second contact area are alternately arranged; wherein, within any 10μm×10μm region of any first contact area, the size of the conductive structure is L1, wherein L1 satisfies: L1≥0.1μm, and the number of conductive structures satisfying L1 is 50 to 1000; and / or, within any 10μm×10μm region of any second contact area, the size of the conductive structure is L1, wherein L1 satisfies: L1≥0.1μm, and the number of conductive structures satisfying L1 is 0 to 50.

[0007] Furthermore, the contact area also includes a third contact area disposed between the first contact area and the second contact area. Along the direction from the first contact area to the second contact area, the third contact area sequentially includes a first contact sub-area, a second contact area, and a third contact area; wherein, the width of the first contact sub-area, the second contact area, and the third contact area are all the same along the length direction of the first contact area, and the total number of conductive structures in the first contact sub-area > the total number of conductive structures in the second contact area > the total number of conductive structures in the third contact area.

[0008] Further, along the length direction of the first contact area, the width of the third contact area is 5μm~200μm; and / or, on the third contact area, the average thickness of the metal electrode is 2μm~20μm; and / or, along the length direction of the first contact area, the sum of the length of the second contact area and the width of the two third contact areas located at both ends of the second contact area is S, the sum of the widths of the two third contact areas located at both ends of a second contact area is 2D, and the ratio of 2D to S is 0.008~0.2.

[0009] Furthermore, the metal electrode includes a plurality of metal particles, wherein the degree of corrosion of the metal particles located in the first contact region in the doped silicon layer is greater than that of the metal particles located in the second contact region.

[0010] Furthermore, the surface of the doped silicon layer has a plurality of pits, the positions of which correspond to the conductive structure, and the number of pits in the second contact region is less than the number of pits in the first contact region.

[0011] Further, along the length direction of the first contact area, the first contact area and the second contact area are alternately arranged; wherein, within any 10μm×10μm region of any first contact area, the size of the pit is L2, wherein L2 satisfies: L2≥50nm, and the number of pits satisfying L2 is 200 to 2000; and / or, within any 10μm×10μm region of any second contact area, the size of the pit is L2, wherein L2 satisfies: L2≥50nm, and the number of pits satisfying L2 is 0 to 199.

[0012] Furthermore, the conductive structure includes a conductive crystal, which is a crystal formed by the aggregation of metal elements in the metal electrode on the doped silicon layer; and / or, the doped silicon layer is an N-type doped layer or a P-type doped layer.

[0013] Furthermore, the metal electrode includes a bus grid line and a collector grid line connected to the bus grid line, the collector grid line is disposed on the first contact area, and the bus grid line is disposed on the second contact area.

[0014] Furthermore, a third contact region is provided between the first contact region and the second contact region, and the collector grid line and the bus grid line are simultaneously provided on the third contact region; and / or, the metal electrode further includes a connection region, and the bus grid line and the collector grid line are simultaneously provided on the connection region, and along the thickness direction of the doped silicon layer, the orthographic projection contour image of the third contact region is located on the orthographic projection contour image of the connection region.

[0015] Secondly, this application discloses a solar cell comprising: the gold-semiconductor contact structure described in any one of the first aspects.

[0016] Furthermore, the solar cell is a back-contact solar cell, a TOPCon solar cell, a PERC solar cell, or an HJT solar cell.

[0017] Thirdly, this application discloses a photovoltaic module, which includes: the solar cell described in any one of the second aspects.

[0018] Compared with the prior art, the beneficial effects of this application are as follows: This application discloses a gold-semiconductor contact structure, a solar cell, and a photovoltaic module. The gold-semiconductor contact structure of this application can improve the passivation performance of the doped silicon layer while ensuring the contact effect between the metal electrode and the doped silicon layer.

[0019] Specifically, the doped silicon layer and the metal electrode in this application are electrically connected through conductive structures. The contact interface between the doped silicon layer and the metal electrode includes a first contact region and a second contact region. The number of conductive structures in the first contact region is greater than that in the second contact region. Therefore, the greater number of conductive structures makes the contact effect between the doped silicon layer and the metal electrode in the first contact region better, which is more conducive to promoting the transport of charge carriers from the doped silicon layer to the metal electrode. Furthermore, the different distribution of the conductive structures in the second contact region and the first contact region, through the relatively fewer conductive structures in the second contact region, also makes the corrosion degree of the doped silicon layer in the second contact region lower, which is more conducive to improving the passivation effect of the doped silicon layer and reducing the recombination loss of charge carriers in the doped silicon layer. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Among them, the scanning electron microscopes in Figures 2, 6 to 8 are scanning electron microscope images obtained by rotating Figure 5 clockwise by a certain angle.

[0021] Figure 1 is a structural schematic diagram of the first type of solar cell provided in the embodiments of this application; Figure 2 is a scanning electron microscope (SEM) image of the gold semi-contact structure at point A in Figure 1; Figure 3 is a top-view structural schematic diagram of the first type of gold semi-contact structure provided in the embodiments of this application; Figure 4 is a structural schematic diagram of the conductive structure provided in the embodiments of this application; Figure 5 is a top-view structural schematic diagram of the second type of gold semi-contact structure provided in the embodiments of this application; Figure 6 is a scanning electron microscope (SEM) image of the gold semi-contact structure provided in the embodiments of this application (the gold semi-contact structure schematically shows the first contact sub-region, the second contact sub-region, and the third contact sub-region in the third contact region); Figure 7 is a scanning electron microscope (SEM) image of the doped silicon layer provided in the embodiments of this application; Figure 8 is an enlarged SEM image of the first contact region in Figure 7; Figure 9 is a structural schematic diagram of the second type of solar cell provided in the embodiments of this application.

[0022] Icons: 100, Silicon substrate; 101, Light-receiving surface; 102, Backlighting surface; 200, Doped silicon layer; 201, First doped silicon layer; 202, Second doped silicon layer; 20, Pits; 300, Metal electrode; 300a, First electrode; 300b, Second electrode; 301, Collector grid line; 302, Bus grid line; 30, Conductive structure; 400, Passivation layer of light-receiving surface; 500, Anti-reflection layer; 600, Dielectric layer; 601, First dielectric layer; 602, Second dielectric layer; 700, Passivation layer of backlighting surface; 1, Gold-semiconductor contact structure; 11, First contact area; 12, Second contact area; 13, Third contact area; 131, First contact sub-area; 132, Second contact sub-area; 133, Third contact sub-area. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0025] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0026] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0027] The technical solutions provided in this application will be further described below with reference to the embodiments and accompanying drawings.

[0028] In the gold-semiconductor contact structure of solar cells, the interfacial contact performance between the metal electrode and the doped silicon layer directly determines the metal electrode's ability to collect charge carriers. Increasing the interfacial contact area between the metal electrode and the charge carriers optimizes the contact effect, achieving a good ohmic contact and thus effectively improving the metal electrode's charge carrier collection efficiency.

[0029] However, during the formation of ohmic contact between the metal electrode and the doped silicon layer, corrosion of the doped silicon layer is often present. Therefore, although a large contact area effectively reduces interfacial contact loss, it also results in a higher degree of corrosion of the doped silicon layer, affecting its passivation performance.

[0030] To address the above issues, this application provides a gold-semiconductor contact structure, a solar cell, and a photovoltaic module. The gold-semiconductor contact structure of this application can improve the passivation performance of the doped silicon layer while ensuring effective contact between the metal electrode and the doped silicon layer. Since the gold-semiconductor contact structure of this application can be applied to solar cells, it will be described in detail below when introducing the solar cell of this application, and will not be described separately.

[0031] As shown in Figures 1 and 2, this application provides a solar cell with a gold semi-contact structure 1. Figure 1 is a schematic diagram of the structure of the first type of solar cell in this application embodiment, and Figure 2 is a scanning electron microscope image of point A in Figure 1. The white particles in Figure 2 are conductive structures 30. The solar cell includes a silicon substrate 100 and a gold semi-contact structure 1 disposed on the silicon substrate 100. The gold semi-contact structure 1 includes: a doped silicon layer 200; and a metal electrode 300. The metal electrode 300 and the doped silicon layer 200 are electrically connected through a plurality of conductive structures 30. The contact interface between the doped silicon layer 200 and the metal electrode 300 includes a first contact region 11 and a second contact region 12. The number of conductive structures 30 in the second contact region 12 is less than the number of conductive structures 30 in the first contact region 11.

[0032] Among them, the doped silicon layer 200 is an N-type doped layer or a P-type doped layer.

[0033] The number of conductive structures 30 can be obtained by scanning electron microscopy (SEM). Before the SEM test, the metal electrode 300 and other film structures on the doped silicon layer 200 are etched away to expose the conductive structures 30 at the contact interface between the doped silicon layer 200 and the metal electrode 300. Then, the corresponding SEM image is obtained by scanning electron microscopy, and the number of conductive structures 30 in the first contact area 11 and the second contact area 12 in the SEM image is counted.

[0034] The conductive structure 30 at the contact interface can be exposed using chemical etching. Specifically, taking silver as an example, the battery cell is first immersed in a nitric acid solution with a volume percentage of 50% to 80% at a temperature of 70°C to 90°C for 5 to 10 minutes. Then, the top layer of silver is peeled off to expose the glass frit in the slurry. Next, the treated battery cell is immersed in hydrofluoric acid with a volume percentage of 3% to 5% at a temperature of 25°C for 2 to 5 minutes to peel off the surface glass frit, exposing the underlying silver dendrites. This application does not limit the specific testing method; any method that achieves the desired effect is acceptable.

[0035] In this application, the doped silicon layer 200 and the metal electrode 300 are electrically connected through a conductive structure 30, and the contact interface between the doped silicon layer 200 and the metal electrode 300 includes a first contact region 11 and a second contact region 12. The number of conductive structures 30 in the second contact region 12 is less than that in the first contact region 11. Therefore, the more conductive structures 30 result in a better contact effect between the doped silicon layer 200 and the metal electrode 300 at the first contact region 11, which is more conducive to promoting the transport of charge carriers from the doped silicon layer 200 to the metal electrode 300. Furthermore, the fewer conductive structures 30 result in a lower corrosion degree of the doped silicon layer 200 at the second contact region 12, which is more conducive to improving the passivation effect of the doped silicon layer 200 and reducing the recombination rate of charge carriers in the doped silicon layer 200.

[0036] In summary, by setting the number of conductive structures 30 in the first contact region 11 to be greater than the number of conductive structures 30 in the second contact region 12, this application helps to ensure the carrier collection capability of the metal electrode 300 and also helps to improve the passivation effect of the doped silicon layer 200, reduce carrier recombination loss, and thus improve the photoelectric conversion efficiency of the solar cell to a greater extent.

[0037] Furthermore, the ratio of the number of conductive structures 30 in the first contact region 11 to the number of conductive structures 30 in the second contact region 12 is M, where M satisfies: 1 < M ≤ 500. By controlling the ratio M of the number of conductive structures 30 in the first contact region 11 and the second contact region 12 to be within the above range, it helps to further ensure the contact performance between the metal electrode 300 and the doped silicon layer 200, and also helps to ensure the passivation effect of the doped silicon layer 200. For example, M can be 50, 100, 200, 300, 400, or 500, etc.

[0038] The number of conductive structures 30 is obtained by obtaining SEM images using the method mentioned above. Then, based on the SEM images, the number of conductive structures 30 in the first contact region 11 and the number of conductive structures 30 in the second contact region 12 within the three 10μm×10μm regions are counted respectively, and the ratio is calculated based on the counted numbers.

[0039] Specifically, based on the obtained SEM image, in the first contact region 11, the number of conductive structures 30 in three 10μm×10μm regions is counted, and the average number of conductive structures 30 in these three regions is calculated. Along the length of the first contact region 11 (see the X direction in Figure 3), these three 10μm×10μm regions are located at both ends and the center of the first contact region 11, respectively. In the second contact region 12, the number of conductive structures 30 in three 10μm×10μm regions is counted, and the average number of conductive structures 30 in these three regions is calculated. Then, the quantity ratio S is calculated based on these two averages. The positions of the three 10μm×10μm regions selected in the second contact region 12 are the same as those in the first contact region 11, and will not be elaborated further here.

[0040] Furthermore, as shown in Figure 3, along the length direction of the first contact area 11, the first contact area 11 and the second contact area 12 are alternately arranged. This alternating arrangement will result in multiple first contact areas 11 and multiple second contact areas 12, and two adjacent first contact areas 11 are separated by one second contact area 12, and two adjacent second contact areas 12 are separated by one first contact area 11.

[0041] Within any 10μm × 10μm region of any first contact region 11, the size of the conductive structure 30 is L1, where L1 ≥ 0.1μm, and the number of conductive structures 30 satisfying L1 is 50 to 1000. By setting the number of conductive structures 30 within the above range, both the metal electrode 300 and the doped silicon layer 200 in any first contact region 11 have good contact performance, thereby helping to improve the carrier collection capability of the metal electrode 300. For example, the number of conductive structures 30 can be 50, 200, 400, 600, 800, or 1000, etc.

[0042] Within any 10μm × 10μm region of any second contact region 12, the size of the conductive structure 30 is L1, where L1 ≥ 0.1μm, and the number of conductive structures 30 satisfying L1 is 0 to 50. By setting the number of conductive structures 30 within the above range, it is more helpful to reduce the degree of corrosion of the doped silicon layer 200 at the second contact region 12, thereby improving the passivation effect of the doped silicon layer 200 to a greater extent and reducing carrier recombination loss. For example, the number of conductive structures 30 can be 0, 10, 20, 30, 40, or 50, etc.

[0043] As shown in Figure 4a), when the conductive structure 30 is a cluster of multiple ellipsoidal or spherical structures, the size L1 of the conductive structure 30 refers to the maximum distance between two relative points in the cluster; as shown in Figure 4b), when the conductive structure 30 is a single ellipsoidal or spherical structure, the size L1 of the conductive structure 30 refers to the maximum distance between two relative points in the single ellipsoidal or spherical structure; as shown in Figure 4c), when the conductive structure 30 is a radial structure, the size L1 of the conductive structure 30 refers to the length of the longest branch in the radial structure.

[0044] Further, as shown in Figures 5 and 6, the dashed lines in Figure 5 are only for better illustration of the third contact area 13 and do not represent the existence of an interface. The contact area of ​​this application also includes a third contact area 13 disposed between the first contact area 11 and the second contact area 12. Along the direction from the first contact area 11 to the second contact area 12 (see X1 direction in Figure 6), the third contact area 13 sequentially includes a first contact sub-region 131, a second contact sub-region 132, and a third contact sub-region 133. The widths D1 of the first contact sub-region 131, D2 of the second contact sub-region 132, and D3 of the third contact sub-region 133 are all the same along the length of the first contact area 11. The total number of conductive structures 30 in the first contact sub-region 131 > the total number of conductive structures 30 in the second contact sub-region 132 > the total number of conductive structures 30 in the third contact sub-region 133.

[0045] By setting the total number of conductive structures 30 in the first contact region 131 to be greater than the total number of conductive structures 30 in the second contact region 132 to be greater than the total number of conductive structures 30 in the third contact region 133, the conductive structures 30 in the third contact region 13 exhibit a decreasing trend in the direction from the first contact region 11 to the second contact region 12. This setting can ensure the contact effect between the doped silicon layer 200 and the metal electrode 300 in the third contact region 13, and also improve the passivation effect of the doped silicon layer 200 in the third contact region 13, thereby significantly improving the photoelectric conversion efficiency of the solar cell.

[0046] Referring back to Figure 5, along the length direction of the first contact region 11, the sum of the length of the second contact region 12 and the width of the two third contact regions 13 located at both ends of the second contact region 12 is S, and the sum of the widths of the two third contact regions located at both ends of a second contact region is 2D. The ratio of 2D to S is 0.008 to 0.2. By controlling the ratio of D to S within the above range, the sizes of the second contact region 12 and the third contact region 13 are appropriate, which helps to ensure the passivation effect of the doped silicon layer 200 at the second contact region 12, and also helps to ensure the passivation performance and carrier transport effect of the doped silicon layer 200 at the third contact region 13 to a high degree. For example, the ratio is 0.008, 0.01, 0.04, 0.08, or 0.2, etc.

[0047] Further, referring back to Figure 6, along the length direction of the first contact region 11, the width D of the third contact region 13 is 5 μm to 100 μm. By controlling the width of the third contact region 13 within the above range, it is more helpful to ensure the passivation capability of the doped silicon layer 200 while ensuring the contact effect between the doped silicon layer 200 and the metal electrode 300, thereby reducing carrier transport losses. For example, the width of the third contact region 13 is 5 μm, 20 μm, 40 μm, 60 μm, or 100 μm, etc.

[0048] Furthermore, the average thickness of the metal electrode 300 on the third contact region 133 is 2 μm to 20 μm. By controlling the thickness of the metal electrode 300 within the above range, it is easier to ensure the carrier collection capability of the metal electrode 300 in the third contact region 133, thereby improving the photoelectric conversion efficiency of the solar cell to a greater extent. For example, the thickness of the metal electrode 300 is 2 μm, 5 μm, 10 μm, 15 μm, or 20 μm, etc.

[0049] The thickness of the metal electrode 300 refers to the total thickness of the metal electrode 300 formed by fusing and sintering the current collector slurry used to form the current collector line 301 and the current collector slurry used to form the current collector line 302. The thickness of the metal electrode 300 can be measured using a 3D microscope. For example, along a direction perpendicular to the length of the first contact region 11 (i.e., the Y direction in Figure 5), the thickness of the metal electrode 300 at the center of the third contact region 133 can be measured, and the average value can be calculated.

[0050] Furthermore, the metal electrode 300 includes several metal particles, and the metal particles located in the first contact region 11 are corroded more severely in the doped silicon layer 200 than the metal particles located in the second contact region 12.

[0051] As shown in Figures 7 and 8, Figure 8 is a magnified scanning electron microscope image of the first contact area 11 in Figure 7. The darker particles in Figure 8 are the pits 20. The presence of the conductive structure 30 at the contact area corrodes the doped silicon layer 200, resulting in pits 20 on the surface of the doped silicon layer 200 after the conductive structure 30 is removed.

[0052] In addition, during the corrosion degree test, the metal electrode 300, other films on the doped silicon layer 200, and the conductive structure 30 on the contact area are first etched away to expose the surface of the doped silicon layer 200. Then, a SEM image of the doped silicon layer 200 is obtained using a scanning electron microscope. The corrosion degree is then measured by counting the number of pits 20 on the surface of the doped silicon layer 200. The counting of pits 20 is performed within a certain area; for example, the number of pits 20 in the first contact area 11 and the number of pits 20 in the second contact area 12 are selected from three 10μm × 10μm areas.

[0053] For example, based on the obtained SEM image, within the first contact region 11, the number of pits 20 in three 10μm × 10μm regions is counted, and the average number of pits 20 in these three regions is calculated. Similarly, within the second contact region 12, the number of pits 20 in three 10μm × 10μm regions is counted, and the average number of pits 20 in these three regions is calculated. These two averages are then used to analyze the degree of corrosion in the first contact region 11 and the second contact region 12. The positions of the three 10μm × 10μm regions in the first contact region 11 and the second contact region 12 are the same as the positions selected for the aforementioned number of tested conductive structures 30, and will not be elaborated further here.

[0054] The significant corrosion at the first contact region 11 indicates good contact performance between the metal electrode 300 and the doped silicon layer 200, resulting in low contact resistivity and facilitating efficient carrier collection. Conversely, the less severe corrosion at the second contact region 12 indicates less damage to the doped silicon layer 200, thus enhancing its passivation effect. Therefore, the synergistic effect of the first and second contact regions 11 not only effectively ensures the carrier collection capability of the metal electrode 300 but also further improves the passivation effect of the doped silicon layer 200, ultimately contributing to higher photoelectric conversion efficiency of the solar cell.

[0055] Furthermore, referring back to Figures 7 and 8, the surface of the doped silicon layer 200 has a number of pits 20, the positions of which correspond to the conductive structure 30. The number of pits 20 in the second contact region 12 is less than the number of pits 20 in the first contact region 11. The fewer pits 20 in the second contact region 12 further reflects the higher integrity of the passivation film layer on the surface of the doped silicon layer 200 at the second contact region 12, resulting in a higher passivation effect of the doped silicon layer 200 at the second contact region 12 and reducing carrier recombination losses.

[0056] Further, referring back to Figure 3, along the length direction of the first contact area 11, the first contact area 11 and the second contact area 12 are alternately arranged. This alternating arrangement will result in multiple first contact areas 11 and multiple second contact areas 12. Two adjacent first contact areas 11 are separated by one second contact area 12, and two adjacent second contact areas 12 are separated by one first contact area 11.

[0057] Within any 10μm × 10μm region of any first contact region 11, the size of the pit is L2, where L2 ≥ 50nm, and the number of pits 20 satisfying L2 is 200 to 2000. By setting the number of conductive structures 30 within the above range, both the metal electrode 300 and the doped silicon layer 200 in any first contact region 11 have good contact performance, thereby helping to improve the carrier collection capability of the metal electrode 300. For example, the number of pits 20 is 200, 500, 1000, 1500, or 2000.

[0058] Within any 10μm × 10μm region of any second contact region 12, the size of the pit is L2, where L2 ≥ 50nm, and the number of pits 20 satisfying L2 is 0 to 199. By setting the number of pits 20 within the above range, it is indicated that the film damage of the doped silicon layer 200 in the second contact region 12 is low, thereby further improving the passivation effect of the doped silicon layer 200. For example, the number of pits 20 is 0, 500, 1000, 1500, or 2000.

[0059] The size of the pit 20 refers to the maximum distance between two opposite points on the pit 20.

[0060] Further, referring back to Figure 5, the metal electrode 300 includes a bus gate 302 and a collector gate 301 connected to the bus gate 302. The collector gate 301 is disposed on the first contact region 11, and the bus gate 302 is disposed on the second contact region 12. The collector gate 301 is used to collect charge carriers in the doped silicon layer 200, and the bus gate 302 is used to transfer the charge carriers collected by the collector gate 301 to an external circuit.

[0061] In order to further ensure the contact effect between the collector grid line 301 and the bus grid line 302, this application also provides a third contact area 13 between the first contact area 11 and the second contact area 12. The third contact area 13 corresponds to the junction of the collector grid line 301 and the bus grid line 302. Therefore, the third contact area 13 is provided with both the collector grid line 301 and the bus grid line 302, thereby ensuring the contact effectiveness between the collector grid line 301 and the bus grid line 302.

[0062] In addition, the metal electrode 300 also includes a connection region, on which both a bus gate 302 and a collector gate 301 are disposed. Furthermore, along the thickness direction of the doped silicon layer 200, the orthographic projection contour image of the third contact region 13 is located on the orthographic projection contour image of the connection region. This arrangement effectively ensures the connection between the bus gate 302 and the collector gate 301, thereby effectively ensuring that the charge carriers collected in the collector gate 301 are transported to the bus gate 302.

[0063] The orthographic projection contour image of the third contact area 13 is located on the orthographic projection contour image of the connecting area. This can be understood as the third contact area 13 and the connecting area having the same area, and their orthographic projection contour images coinciding. Alternatively, it can be understood as the orthographic projection contour image of the third contact area 13 being located inside the orthographic projection contour image of the connecting area, meaning the area of ​​the third contact area 13 is smaller than that of the connecting area.

[0064] Additionally, referring back to Figure 5, the region with the collector grid line 301 includes a first contact region 11 and a third contact region 13. The third contact region 13 refers to the region extending from the edge of the region with the bus grid line 302 into the region to a specified width D. For example, when D is 5 μm, the width of the third contact region 13 is 5 μm. Furthermore, along the direction perpendicular to the length of the first contact region 11, i.e., the Y direction in Figure 5, the width of the third contact region 13 is equal to the distance of the first contact region 11 in the Y direction.

[0065] The preparation method of gold semi-contact structure is briefly described below.

[0066] The method for preparing the gold-semiconductor contact structure includes the following steps: printing, printing a paste for making a metal electrode on a passivation layer; sintering, making the paste of the metal electrode contact a doped silicon layer, and forming a first contact interface and a second contact interface on the contact interface, and forming a conductive precursor on the first contact interface and the second contact interface; photoinjection, transforming the conductive precursor into a conductive structure, and making the number of conductive structures on the first contact interface less than that on the second contact interface, thereby obtaining the above-mentioned gold-semiconductor contact structure.

[0067] This application does not limit the specific preparation method of the gold semicontact structure, as long as it can achieve the effect of this application.

[0068] Further, the printing step includes: printing a busbar paste for preparing busbars on a doped silicon layer, the busbar paste comprising inert glass frit, active glass powder, metal particles and an organic carrier; pre-sintering the busbar paste; and printing a collector grid paste for preparing collector grids on the doped silicon layer and a portion of the busbar paste, the collector grid paste comprising active glass powder, an organic carrier and metal particles.

[0069] In this process, inert glass powder is added to the busbar paste used to prepare the busbars. As a result, when printing the collector grid paste, the inert glass powder allows the collector grid paste printed on the busbar paste to penetrate downwards and contact the surface of the doped silicon layer to form a conductive structure, thus forming a third contact area that contains both busbars and collector grids.

[0070] In addition, inert glass powder includes the SiO2–Al2O3–B2O3 system; active glass powder includes the Bi2O3–ZnO–B2O3 system.

[0071] Furthermore, in the busbar slurry, the organic carrier comprises 5%–11.7% by mass, the active glass powder comprises 0.05%–0.2% by mass, the inert glass powder comprises 1%–5% by mass, and the metal particles comprise 86%–90% by mass. By controlling the content of each component in the busbar slurry within the above ranges, it is helpful to ensure the performance of the prepared busbar; moreover, it can also ensure the quality of the third contact region to a high degree, thereby further improving the photoelectric conversion efficiency of the solar cell.

[0072] In the current collector grid paste, the organic carrier has a mass percentage of 5% to 10%, the active glass powder has a mass percentage of 3% to 5%, and the metal particles have a mass percentage of 85% to 90%. By controlling the content of each component in the current collector grid paste within the above ranges, it helps to ensure the performance of the prepared current collector grid, and to a greater extent ensure the contact performance between the doped silicon layer and the current collector grid at the first contact region, thereby helping to further improve the current collector grid's ability to collect charge carriers.

[0073] In addition, the pre-sintering temperature is 500℃~650℃. By controlling the pre-sintering temperature within the above range, the busbar paste is solidified, thereby avoiding the risk of the current collector paste and busbar paste spreading during the printing of the current collector paste. This effectively controls the size of the formed third contact area, thus ensuring both the collection effect of the metal electrode on the charge carriers and the passivation effect of the doped silicon layer.

[0074] Furthermore, in the sintering step, the sintering temperature is 650℃~850℃. By controlling the sintering temperature within this range, it is helpful to ensure the quality of the formed conductive structure to a higher extent, which in turn helps to improve the metal electrode's ability to collect charge carriers.

[0075] In addition, the light injection steps include: first heating the conductive precursor; second heating the conductive precursor; and illumination; wherein the peak temperature of the first heating is 180℃~620℃. By controlling the peak temperature of the first heating within the above range, it is easier to ensure the quality of the formed gold-semiconductor contact structure, thereby improving the photoelectric conversion efficiency of the solar cell to a greater extent.

[0076] The peak temperature of the second heating is 80℃~320℃, and the energy density of the light is 12 kW / m². 2 ~120 kW / m 2 The illumination wavelength is within a continuous spectral band of 500 nm to 1100 nm. By controlling the peak temperature of the second heating and the illumination parameters within the above range, it is easier to ensure the quality of the formed gold-semiconductor contact structure, thereby improving the photoelectric conversion efficiency of the solar cell to a greater extent.

[0077] This application also discloses a solar cell, which includes the aforementioned gold-semiconductor contact structure.

[0078] Furthermore, the solar cells are back-contact solar cells, TOPCon solar cells, PERC solar cells, or HJT solar cells.

[0079] Furthermore, the doped silicon layer of this application includes a first doped silicon layer and a second doped silicon layer with different conductivity types; the metal electrode includes a first electrode and a second electrode. In a first optional embodiment, the first doped silicon layer and the first electrode are the gold-semiconductor contact structure of this application; in a second optional embodiment, the first doped silicon layer and the first electrode, the second doped silicon layer and the second electrode are all the gold-semiconductor contact structures of this application.

[0080] Referring to Figure 9, which shows a solar cell in the first optional embodiment, the gold-semiconductor contact structure 1 of this application includes a first doped silicon layer 201 and a first electrode 300a disposed on the backlight surface 102 of the silicon substrate 100. This solar cell is a TOPCon solar cell. The structure of a TOPCon solar cell includes: a silicon substrate 100, including a light-receiving surface 101 and a backlight surface 102 disposed opposite to each other; a first doped silicon layer 201 disposed on the backlight surface, and a second doped silicon layer 202 disposed on the light-receiving surface 101 of the silicon substrate 100; and a second doped silicon layer 202 disposed sequentially on the second doped silicon layer... The light-receiving passivation layer 400 and the anti-reflection layer 500 on the silicon substrate 100; the dielectric layer 600 is sequentially disposed between the backlight surface 102 and the first doped silicon layer 201 on the silicon substrate 100; and the backlight passivation layer 700 is disposed on the side of the first doped silicon layer 201 away from the dielectric layer 600; wherein, the second electrode 300b of the metal electrode 300 passes through the light-receiving passivation layer 400 and the anti-reflection layer 500 on the second doped silicon layer 202 and makes ohmic contact with the second doped silicon layer 202; the first electrode 300a passes through the backlight passivation layer 700 on the first doped silicon layer 201 and makes ohmic contact with the first doped silicon layer 201.

[0081] Referring back to Figure 1, Figure 1 shows a solar cell in the second optional embodiment, namely the gold-semiconductor contact structure 1 of this application, which includes a first doped silicon layer 201 and a first electrode 300a, and a second doped silicon layer 202 and a second electrode 300b, simultaneously disposed on the back surface 102 of the silicon substrate 100. This solar cell is a back-contact solar cell. The structure of the back-contact solar cell includes: a silicon substrate 100, with a light-receiving surface 101 of the silicon substrate 100 sequentially disposed with a light-receiving surface passivation layer 400 and an anti-reflection layer 500; the back surface 102 of the silicon substrate 100 includes an N-type conductive region and a P-type conductive region, and an isolation region disposed between the N-type conductive region and the P-type conductive region; wherein, the dielectric layer 600 includes a first dielectric layer 601 disposed on the N-type conductive region and a second dielectric layer 602 disposed on the P-type conductive region, and the surface of the first dielectric layer 601 facing away from the silicon substrate 100 is provided with The back contact solar cell includes a first doped silicon layer 201 and a second doped silicon layer 202 on the surface of the second dielectric layer 602 facing away from the silicon substrate 100. The first doped silicon layer 201 is doped with an N-type dopant element, and the second doped silicon layer 202 is doped with a P-type dopant element. The back contact solar cell also includes a backlight passivation layer 700 disposed on the first doped silicon layer 201, the second doped silicon layer 202, and the isolation region. The first electrode 300a of the metal electrode 300 passes through the backlight passivation layer 700 in the N-type conductive region and makes ohmic contact with the first doped silicon layer 201, so that the first electrode 300a and the first doped silicon layer 201 form a first gold-semi-contact structure. The second electrode 300b passes through the backlight passivation layer 700 in the P-type conductive region and makes ohmic contact with the second doped silicon layer 202, so that the second electrode 300b and the second doped silicon layer 202 form a second gold-semi-contact structure.

[0082] This application also discloses a photovoltaic module, which includes the aforementioned solar cell.

[0083] The technical solution of this application will be further explained below with reference to more specific embodiments and experimental test results.

[0084] Example 1: This example provides a solar cell with a gold semi-contact structure. The preparation method includes the following steps: Preparing a solar cell semi-finished product: Cleaning the surface of an N-type silicon substrate.

[0085] A silicon oxide dielectric layer with a thickness of 1 nm to 3 nm and a P-type doped silicon layer with a thickness of 200 nm and doped with boron are prepared on the back surface of a silicon substrate.

[0086] First patterning process: A laser is used to remove the P-type doped silicon layer and the first dielectric layer in some areas, exposing the backlight surface of the silicon substrate in some areas. Then, a tank-type alkaline polishing machine is used to clean the exposed silicon substrate.

[0087] A second dielectric layer of silicon oxide with a thickness of 1 nm to 3 nm and an N-type doped silicon layer with a thickness of 180 nm and doped with phosphorus are prepared on the exposed backlight surface.

[0088] Second patterning process: Remove part of the N-type doped silicon layer and the second dielectric layer to form an isolation region between the N-type doped silicon layer and the P-type doped silicon layer.

[0089] A pyramid structure is fabricated by texturing the isolation region and the light-receiving surface of the silicon substrate; an anti-reflection layer consisting of an aluminum oxide passivation layer, silicon oxide, silicon oxynitride, and silicon nitride is sequentially fabricated on the light-receiving surface; and a backlight passivation layer consisting of an aluminum oxide passivation layer and a silicon oxynitride stack is fabricated on the backlight surface.

[0090] Fabrication of gold-semi-contact structures on semi-finished solar cells: Printing: Busbar paste for fabricating busbars is printed on silicon nitride layers with N-type doped silicon layers and P-type doped silicon layers. The busbar paste includes inert glass frit, active glass powder, metal particles, and an organic carrier; wherein, the metal particles are spherical silver powder with a D50 of 0.5μm~2.5μm and a mass percentage of 88%; the inert glass powder is a SiO2–Al2O3–B2O3 system, and the mass percentage of inert glass powder in the busbar paste is 3.9%; the active glass powder is a Bi2O3–ZnO–B2O3 system, and the mass percentage of active glass powder in the busbar paste is [missing information]. 0.1%; the organic carrier has a mass percentage of 8% in the busbar paste; the first electrode paste and busbar paste are pre-sintered at a pre-sintering temperature of 600℃; a current collector paste for preparing the current collector is printed on the doped silicon layer and part of the busbar paste. The current collector paste includes active glass powder, organic carrier, and metal particles; wherein, the metal particles are a mixture of spherical and flake silver powder with a D50 of 0.5μm~2μm and a mass percentage of 88%; the active glass powder is a PbO–Bi2O3–ZnO system, and the active glass powder has a mass percentage of 4% in the current collector paste; the organic carrier has a mass percentage of 8% in the current collector paste.

[0091] Sintering is performed to bring the slurry of the metal electrode into contact with the doped silicon layer, forming a first contact interface and a second contact interface on the contact interface, and forming a conductive precursor at the first contact interface and the second contact interface. The sintering temperature is 750°C.

[0092] Light injection transforms the conductive precursor into a conductive structure, reducing the number of conductive structures at the first contact interface to less than at the second contact interface. The conductive precursor undergoes a first heating process with a peak temperature of 180℃~620℃. A second heating process followed by light irradiation occurs, with the second heating reaching a peak temperature of 200℃ and the light irradiation having an energy density of 80 kW / m². 2The light is applied in a continuous spectral band with a wavelength of 800 nm; the aforementioned gold-semiconductor contact structure is obtained; wherein, in this gold-semiconductor contact structure, the number of conductive structures in the second contact region is less than the number of conductive structures in the first contact region, the degree of etching of the doped silicon layer at the first contact region is greater than the degree of etching in the second contact region, the number of pits in the second contact region is less than the number of pits in the first contact region; and the ratio of the number of conductive structures in the first contact region to the number of conductive structures in the second contact region is 500:1 to 30:1, and any 10μm × 10μm of any first contact region... Within the region, the number of conductive structures is 300 to 500 and the number of pits is 800 to 1500; within any 10μm × 10μm region of any second contact region, the number of conductive structures is 1 to 10 and the number of pits is 10 to 150; the sum of the length of the second contact region and the width of the two third contact regions located at both ends of the second contact region is S, the width of the two third contact regions is 2D, the ratio of 2D to S is 0.008 to 0.2, and the width of the third contact region is 10μm to 20μm.

[0093] Example 2: The only difference between this example and Example 1 is that the number of conductive structures in the 10μm×10μm region of the first contact region is 300 to 500, and the number of conductive structures in the 10μm×10μm region of the second contact region is 30 to 50. The ratio of the number of conductive structures in the first contact region to the number of conductive structures in the second contact region is 6:1 to 10:1.

[0094] Example 3: The only difference between this example and Example 1 is that the number of conductive structures in the 10μm×10μm region of the first contact region is 80 to 200, and the number of conductive structures in the 10μm×10μm region of the second contact region is 10 to 40. The ratio of the number of conductive structures in the first contact region to the number of conductive structures in the second contact region is 2:1 to 20:1.

[0095] Comparative Example 1: The only difference between this comparative example and Example 1 is that the number of conductive structures in the 10μm×10μm region of the first contact region is 20 to 100, and the number of conductive structures in the 10μm×10μm region of the second contact region is 100 to 200. The ratio of the number of conductive structures in the first contact region to the number of conductive structures in the second contact region is 1:10 to 1:1.

[0096] Test method: Test of the number of conductive structures: First, the metal electrode, silicon oxynitride layer and aluminum oxide film layer are etched away to expose the contact area. SEM images are taken and the number of conductive structures is counted in three 10μm×10μm areas at both ends and the center of any first contact area along its length. The number of conductive structures is counted in three 10μm×10μm areas at both ends and the center of any second contact area along its length.

[0097] Test for the number of pits: First, the metal electrode, silicon oxynitride layer, aluminum oxide film layer, and conductive structure are etched away, and SEM images are obtained. The number of pits is counted in three 10μm×10μm areas at both ends and the center of any first contact area along the length direction. The number of pits is also counted in three 10μm×10μm areas at both ends and the center of any second contact area along the length direction.

[0098] The parameter variations of Examples 1 to 3 and Comparative Example 1 are shown in Table 1 below.

[0099] Table 1. Parameters of the gold-semiconductor contact structures in Examples 1 to 3 and Comparative Example 1

[0100] Performance Testing: The solar cells prepared in Examples 1 to 3 and Comparative Example 1 were subjected to the following related tests: This application uses a Halm test and sorting device to perform performance tests on a solar cell, including open-circuit voltage, short-circuit current, and fill factor. The Halm device is a device that simulates sunlight, and is equipped with electronic loads, data acquisition and calculation equipment, etc., to test the electrical performance of photovoltaic devices (including solar cells). The silicon wafer of the solar cell used for control testing was 182mm, and the calibrated light intensity was 1000±5 W / m². The experimental test results are shown in Table 2 below. Table 2 shows the performance test results of the solar cell.

[0101] Table 2 Performance test results of solar cells

[0102] Comparing the data from Examples 1 to 3 with Comparative Example 1, it can be seen that the photoelectric conversion efficiency of Examples 1 to 3 is better than that of Comparative Example 1. This demonstrates that controlling the number of conductive structures in the first contact region to be greater than that in the second contact region effectively utilizes the high contact performance between the doped silicon layer and the metal electrode in the first contact region to improve carrier transport; and effectively utilizes the high passivation effect of the doped silicon layer in the second contact region to reduce carrier recombination losses.

[0103] This application provides a detailed description of the gold-semiconductor contact structure, solar cell, and photovoltaic module disclosed in the embodiments. Specific examples are used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the gold-semiconductor contact structure, solar cell, and photovoltaic module. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A gold-semiconductor contact structure, characterized in that, The gold-semiconductor contact structure includes: a doped silicon layer; a metal electrode, wherein the metal electrode and the doped silicon layer are electrically connected through a plurality of conductive structures; wherein the contact interface between the doped silicon layer and the metal electrode includes a first contact region and a second contact region, and the number of conductive structures in the second contact region is less than the number of conductive structures in the first contact region.

2. The gold-semiconductor contact structure according to claim 1, characterized in that, The ratio of the number of conductive structures in the first contact region to the number of conductive structures in the second contact region is M, where M satisfies: 1 < M ≤ 500.

3. The gold-semiconductor contact structure according to claim 1, characterized in that, Along the length of the first contact area, the first contact area and the second contact area are alternately arranged; wherein, within any 10μm×10μm region of any first contact area, the size of the conductive structure is L1, wherein L1 satisfies: L1≥0.1μm, and the number of conductive structures satisfying L1 is 50 to 1000; and / or, within any 10μm×10μm region of any second contact area, the size of the conductive structure is L1, wherein L1 satisfies: L1≥0.1μm, and the number of conductive structures satisfying L1 is 0 to 50.

4. The gold-semiconductor contact structure according to claim 1, characterized in that, The contact area further includes a third contact area disposed between the first contact area and the second contact area. Along the direction from the first contact area to the second contact area, the third contact area sequentially includes a first contact sub-area, a second contact area, and a third contact area; wherein, the width of the first contact sub-area, the second contact area, and the third contact area are all the same along the length direction of the first contact area, and the total number of conductive structures in the first contact sub-area > the total number of conductive structures in the second contact area > the total number of conductive structures in the third contact area.

5. The gold-semiconductor contact structure according to claim 4, characterized in that, Along the length direction of the first contact area, the width of the third contact area is 5μm to 200μm; and / or, on the third contact area, the average thickness of the metal electrode is 2μm to 20μm; and / or, along the length direction of the first contact area, the sum of the length of the second contact area and the width of the two third contact areas located at both ends of the second contact area is S, the sum of the widths of the two third contact areas located at both ends of a second contact area is 2D, and the ratio of 2D to S is 0.008 to 0.

2.

6. The gold-semiconductor contact structure according to claim 1, characterized in that, The metal electrode includes a plurality of metal particles, and the degree of corrosion of the metal particles located in the first contact area in the doped silicon layer is greater than that of the metal particles located in the second contact area.

7. The gold-semiconductor contact structure according to claim 1, characterized in that, The surface of the doped silicon layer has a number of pits, the positions of which correspond to the conductive structure, and the number of pits in the second contact region is less than the number of pits in the first contact region.

8. The gold-semiconductor contact structure according to claim 7, characterized in that, Along the length of the first contact area, the first contact area and the second contact area are alternately arranged; wherein, within any 10μm×10μm region of any first contact area, the size of the pit is L2, wherein L2 satisfies: L2≥50nm, and the number of pits satisfying L2 is 200 to 2000; and / or, within any 10μm×10μm region of any second contact area, the size of the pit is L2, wherein L2 satisfies: L2≥50nm, and the number of pits satisfying L2 is 0 to 199.

9. The gold-semiconductor contact structure according to claim 1, characterized in that, The conductive structure includes a conductive crystal, which is a crystal formed by the aggregation of metal elements in the metal electrode on the doped silicon layer; and / or, the doped silicon layer is an N-type doped layer or a P-type doped layer.

10. The gold-semiconductor contact structure according to any one of claims 1 to 9, characterized in that, The metal electrode includes a bus grid line and a collector grid line connected to the bus grid line. The collector grid line is disposed on the first contact area, and the bus grid line is disposed on the second contact area.

11. The gold-semiconductor contact structure according to claim 10, characterized in that, A third contact region is further provided between the first contact region and the second contact region, and the collector grid line and the bus grid line are simultaneously provided on the third contact region; and / or, the metal electrode further includes a connection region, and the bus grid line and the collector grid line are simultaneously provided on the connection region, and along the thickness direction of the doped silicon layer, the orthographic projection contour image of the third contact region is located on the orthographic projection contour image of the connection region.

12. A solar cell, characterized in that, The solar cell includes: the gold-semiconductor contact structure as described in any one of claims 1 to 11.

13. The solar cell according to claim 12, characterized in that, The solar cell is a back-contact solar cell, TOPCon solar cell, PERC solar cell, or HJT solar cell.

14. A photovoltaic module, characterized in that, The photovoltaic module includes: the solar cell according to any one of claims 12 to 13.

Images