Solar cell and passivated contact structure thereof

Abstract

The present disclosure relates to the technical field of solar cells, and discloses a solar cell and a passivation contact structure thereof. The passivation contact structure comprises: first to Nth passivation contact units and a surface passivation layer, which are sequentially stacked on a base layer; any passivation contact unit comprises a passivation layer and a doped layer which are stacked, the thicknesses of the plurality of passivation layers sequentially decrease and / or the porosities of the plurality of passivation layers sequentially increase in a stacking direction from the surface of the base layer to the outside; the surface passivation layer is formed on the Nth passivation contact unit, the thickness of the surface passivation layer is less than that of the Nth passivation layer and / or the porosity of the surface passivation layer is greater than that of the Nth passivation layer. According to the design requirements of the doped layer, the present disclosure sets the passivation layer at each contact interface of the doped layer to realize the optimization of the interface passivation performance, so as to ensure the gradual doping gradient of the doped layer and take into account the optical performance and the electrical performance.

Description

Technical Field

[0001] This disclosure relates to the field of solar cell technology, specifically to a solar cell and its passivated contact structure. Background Technology

[0002] In the current high-efficiency crystalline silicon photovoltaic cell industry, such as tunneling oxide passivated contact cells (TOPCon cells) and tunneling oxide passivated back contact cells (TBC cells), tunneling oxide and doped polycrystalline silicon (poly-Si) layers are usually used as passivation contact structures. With their excellent carrier passivation performance, they promote the dual improvement of mass production yield and conversion efficiency.

[0003] Currently, to reduce the contact resistance between the metal electrode and poly-Si in passivated contact batteries and decrease the lateral transport loss of charge carriers within the poly-Si layer, related technologies typically increase the thickness of the poly-Si layer. However, a thicker poly-Si layer significantly exacerbates the parasitic absorption effect on incident light, resulting in the loss of a large number of photons that should be absorbed by the silicon substrate to excite photogenerated charge carriers, severely limiting the improvement of the battery's optical performance. Maintaining a thinner poly-Si layer to reduce parasitic absorption, and then widening the sintering window of the paste to ensure contact performance, is another approach. However, conventional tunneling oxide layers cannot simultaneously meet multiple requirements. First, it is difficult to balance the selective transmission of dopant atoms and the blocking of impurity atoms. Dopant atoms need to form a gradient doping effect to enhance field-effect passivation, while impurity atoms need to be blocked to prevent excessive accumulation at the silicon substrate interface, which would damage the passivation quality. Second, the embedding depth of metal particles must be controlled during the sintering stage to ensure that the metal effectively penetrates the poly-Si for good charge carrier collection while preventing excessive metal from burning through into the silicon substrate and causing a surge in contact recombination.

[0004] In summary, the current passivation contact structure process in solar cells has a narrow adaptation window, making it difficult to maintain excellent passivation and contact performance while optimizing optical performance, which severely restricts the photoelectric conversion efficiency of passivated contact solar cells. Summary of the Invention

[0005] This disclosure provides a solar cell and its passivation contact structure to solve the problem that existing solar cell passivation contact structures cannot simultaneously achieve optical performance and passivation contact performance.

[0006] In a first aspect, this disclosure provides a passivation contact structure for a solar cell, including a plurality of passivation contact units and a surface passivation layer. The plurality of passivation contact units are stacked sequentially on a substrate layer, including a first passivation contact unit to an Nth passivation contact unit, where N is an integer greater than or equal to 2. Each passivation contact unit includes a stacked passivation layer and a doped layer, wherein the passivation layer is disposed relatively close to the substrate layer. In a stacking direction from the surface of the substrate layer outward, the thickness of the plurality of passivation layers decreases sequentially, and / or the porosity of the plurality of passivation layers increases sequentially. The surface passivation layer is formed on the surface of the Nth passivation contact unit that is relatively far from the substrate layer. The thickness of the surface passivation layer is less than the thickness of the Nth passivation layer, and / or the porosity of the surface passivation layer is greater than the porosity of the Nth passivation layer.

[0007] Beneficial Effects: In this disclosure, multiple passivation contact units firstly comprise different doped layers in the direction of doped atom diffusion from the outside to the inside, balancing improved contact performance with reduced parasitic absorption. Based on this, passivation layers are set at each contact interface of the doped layer according to the design requirements of the doped layer to achieve interface optimization and ensure a gradual doping gradient. Furthermore, the multilayer passivation layer of the passivation contact structure includes passivation layers for the inner passivation contact units and an outer surface passivation layer, designed with decreasing thickness and increasing porosity from the inside to the outside. That is, relatively thin passivation layers are configured with relatively large porosity, while relatively thick passivation layers are configured with relatively small porosity. These different passivation layers are set between different layers along the stacking direction to optimize the doping performance of each doped layer and the surface expansion layer of the substrate layer, thereby balancing the overall optical and electrical performance of the passivation contact structure.

[0008] In one optional embodiment, the plurality of passivation contact units include a first passivation contact unit and a second passivation contact unit. The first passivation contact unit is adapted to be formed on a substrate layer and includes a first passivation layer and a first doped layer, with the first passivation layer disposed relatively close to the substrate layer. The second passivation contact unit is formed on the side of the first passivation contact unit that is relatively far from the substrate layer and includes a second passivation layer and a second doped layer, with the second passivation layer disposed relatively close to the first passivation contact unit. The thicknesses of the first passivation layer, the second passivation layer, and the surface passivation layer decrease sequentially, and the porosity of the first passivation layer, the second passivation layer, and the surface passivation layer increases sequentially.

[0009] Beneficial effects: This disclosure firstly forms two doped layers with different doping concentrations through a second passivation layer in the direction of doped atom diffusion from the outside to the inside, thus balancing improved contact performance and reduced parasitic absorption. For example, the second doped layer with a higher doping concentration on the outside directly contacts the external electrode paste, resulting in low contact resistance and helping to ensure electrical performance; while the first contact layer on the inside, which is relatively close to the substrate layer, has a lower doping concentration and less parasitic absorption, helping to ensure optical performance.

[0010] Based on this, this disclosure provides passivation layers at the upper and lower interfaces of each of the aforementioned doped layers. For example, the first passivation layer optimizes the passivation effect at the interface between the first doped layer and the substrate layer, the second passivation layer optimizes the passivation effect at the interface between the first doped layer and the second doped layer, and the outermost passivation layer optimizes the passivation effect on the outer surface of the second doped layer. In other words, passivation layers are provided at each contact interface of the doped layer according to the design requirements of the doped layer to achieve interface optimization, while ensuring the gradual doping gradient of the doped layer. Furthermore, the three passivation layers of the aforementioned passivated contact structure are designed with decreasing thickness and increasing porosity from the inside out. That is, relatively thin passivation layers are configured with relatively large porosity, and relatively thick passivation layers are configured with relatively small porosity. These different passivation layers are placed between different layers along the stacking direction to optimize the doping performance of the second doped layer, the first doped layer, and the inner extension layer on the surface of the substrate layer, thereby taking into account both the overall optical and electrical performance of the passivated contact structure.

[0011] In one optional embodiment, the thickness of the first passivation layer ranges from 2 to 5 nm, the thickness of the second passivation layer ranges from 0.2 to 2 nm, and the thickness of the surface passivation layer is less than 0.2 nm.

[0012] Beneficial effects: Within the above thickness range, each passivation layer can achieve a balance between electrical and optical performance to the greatest extent, optimizing the overall passivation contact performance of the battery.

[0013] In one optional embodiment, the first passivation layer has a plurality of first pores, the second passivation layer has a plurality of second pores, and the surface passivation layer has a plurality of surface pores; the lateral dimensions of the first pores, the second pores, and the surface pores increase sequentially.

[0014] Beneficial effects: The porosity of each passivation layer can be controlled by designing the lateral dimensions of the pores in each passivation layer. The results are highly visualized, simple and convenient to control, and have a large control window.

[0015] In one alternative implementation, the lateral dimension of the surface pores is less than 0.5 μm.

[0016] Beneficial effect: that is, limiting the maximum value of the surface pore with the largest lateral size among the first pore, the second pore and the surface pore. This maximum value is limited to 0.5μm to ensure that most doped atoms cannot pass through, so that the three passivation layers can achieve sufficient blocking effect while achieving the maximum relative permeability of the outermost layer.

[0017] In one optional embodiment, the passivation contact structure includes a contact area and a non-contact area, and an electrode structure is adapted to be disposed on the contact area; in the same passivation layer, the porosity of the contact area is greater than that of the non-contact area; and in the stacking direction from the surface of the substrate layer outward, the porosity of the multiple contact areas increases sequentially, and the porosity of the multiple non-contact areas increases sequentially.

[0018] Beneficial effects: The passivated contact structure is divided into contact and non-contact regions. For the contact region, priority is given to carrier collection performance, while for the non-contact region, passivation performance is prioritized. On the one hand, a larger porosity in the contact region facilitates the penetration of metal particles through the entire doped layer, thereby achieving effective carrier collection. On the other hand, the smaller porosity in the non-contact region allows impurity diffusion atoms to penetrate, but it cannot effectively allow metal particles to penetrate.

[0019] In one alternative embodiment, the lateral dimension of the pores located in the contact area is larger than that of the pores located in the non-contact area; and in the stacking direction from the surface of the substrate outward, the lateral dimensions of the pores in the multiple contact areas increase sequentially, and the lateral dimensions of the pores in the multiple non-contact areas increase sequentially.

[0020] Beneficial effects: Differentiated design of porosity in different regions can be achieved by adjusting the lateral size of the pores. The structure is simple and the control window is large.

[0021] In one alternative implementation, the thickness of the multiple doped layers increases sequentially in the stacking direction from the surface of the substrate layer outward.

[0022] Beneficial effects: The outer doped layer that is in direct contact with the metal electrode is thicker to ensure contact performance; correspondingly, the inner doped layer that is not in contact with the metal electrode is designed to be thinner, thereby reducing the overall thickness of the doped layer, that is, reducing parasitic absorption within the doped layer, and ensuring photoelectric conversion efficiency and carrier collection.

[0023] In one alternative implementation, the multiple doped layers have the same doping type.

[0024] Beneficial effects: The above-mentioned design of multiple doped layers and multiple passivation layers is integrated into a passivation contact structure with the same doping type, which helps to optimize the direct application of passivation contact structures in various types of batteries.

[0025] In one alternative implementation, the doping concentration of the multiple doped layers increases sequentially in the stacking direction from the surface of the substrate layer outward; and the doping concentration within any doped layer gradually increases.

[0026] Beneficial effects: With the doping concentration of the inner doped layer being lower than that of the outer doped layer, and taking into account both contact performance and parasitic absorption, each doped layer itself is also set to have a gradual gradient change in doping concentration from the outside to the inside, further optimizing contact performance and optical performance.

[0027] In one alternative embodiment, it further includes: a first passivation antireflection layer formed on the side of the surface passivation layer that is relatively far from the substrate layer.

[0028] Beneficial effects: The first passivation antireflection layer helps reduce light reflection on the surface of the passivated contact structure and achieves surface protection for the passivated contact structure.

[0029] Secondly, this disclosure also provides a solar cell, comprising: a substrate layer, a first passivation contact structure and a second passivation contact structure, a first electrode and a second electrode, wherein the first passivation contact structure and the second passivation contact structure are respectively formed on opposite sides of the substrate layer, or alternately formed on one side of the substrate layer; the doping types of the first passivation contact structure and the second passivation contact structure are opposite; at least one of the first passivation contact structure and the second passivation contact structure employs the aforementioned passivation contact structure; the first electrode is disposed on the first passivation contact structure, and the second electrode is disposed on the second passivation contact structure.

[0030] Beneficial effects: The passivation contact structure described above can be applied to various cell structures such as conventional TOPCon cells, HJT cells, and back contact cells; in solar cells, two passivation contact structures with different doping types can be used, one of which can adopt the passivation contact structure designed by the multi-layer gradient above, and the other can adopt a conventional passivation contact structure; or both can adopt the passivation contact structure designed by the multi-layer gradient above, further optimizing the overall passivation contact performance of the cell and thus improving power generation efficiency. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the specific embodiments of this disclosure or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the passivated contact structure according to an embodiment of the present disclosure; Figure 2 This is a schematic diagram of the passivation contact structure according to an embodiment of the present disclosure, with different configurations in the contact area and non-contact area; Figure 3 This is a schematic diagram of the passivation contact structure in an embodiment of the present disclosure when it has a first passivation antireflection layer; Figure 4 This is a schematic diagram of the structure of a solar cell according to an embodiment of this disclosure.

[0033] Explanation of reference numerals in the attached figures: 10. Substrate layer; 101. Light-receiving surface; 102. Backlight-receiving surface; 20. Passivated contact structure; 201. First passivated contact structure; 202. Second passivated contact structure; 301. First electrode; 302. Second electrode; 40. Second passivation antireflection layer; 1. First passivation contact unit; 11. First passivation layer; 111. First pore; 12. First doped layer; 2. Second passivation contact unit; 21. Second passivation layer; 211. Second pore; 22. Second doped layer; 31. Surface passivation layer; 311. Surface pore; 4. First passivation antireflection layer; A. Contact area; B. Non-contact area. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0035] refer to Figures 1 to 3 This disclosure provides a passivation contact structure 20 for a solar cell, comprising: a plurality of passivation contact units and a surface passivation layer 31 sequentially stacked on a substrate layer 10, wherein the plurality of passivation contact units include a first passivation contact unit 1 to an Nth passivation contact unit, where N is an integer greater than or equal to 2; each passivation contact unit includes a stacked passivation layer and a doped layer, wherein the passivation layer is disposed relatively close to the substrate layer; in a stacking direction outward from the surface of the substrate layer 10, the thickness of the plurality of passivation layers decreases sequentially, and / or the porosity of the plurality of passivation layers increases sequentially; the surface passivation layer 31 is formed on the surface of the Nth passivation contact unit relatively far from the substrate layer 10, the thickness of the surface passivation layer 31 is less than the thickness of the Nth passivation layer, and / or the porosity of the surface passivation layer 31 is greater than the porosity of the Nth passivation layer.

[0036] Specifically, this disclosure defines a passivation contact structure consisting of multiple passivation contact units and an outermost surface passivation layer 31. Each passivation contact unit may include a passivation layer relatively close to the substrate layer 10 and a doped layer disposed on the passivation layer. The passivation layer may be an ultrathin silicon dioxide layer, and the doped layer may be a doped polycrystalline silicon layer. In other embodiments, the passivation layer may also be made of materials such as silicon nitride, silicon oxynitride, or aluminum oxide. The materials of the passivation layers in the passivation contact units and the multilayer passivation layers of the surface passivation layer 31 may be the same or different. The number of passivation contact units can be specifically set according to design requirements, such as two, three, four, or more.

[0037] In this disclosure, multiple passivated contact units include different doped layers in the direction of atomic diffusion from the outside to the inside, such as having different doping concentrations, to balance improved contact performance and reduced parasitic absorption. For example, the doped layer with a higher doping concentration on the outside directly contacts the external electrode paste, resulting in low contact resistance and helping to ensure electrical performance; while the doped layer on the inside, relatively close to the substrate layer 10, has a lower doping concentration, resulting in less parasitic absorption and helping to ensure optical performance. Based on this, this disclosure provides passivation layers on the upper and lower interfaces of each of the above-mentioned doped layers to optimize the passivation effect of different contact interfaces. That is, according to the design requirements of the doped layer, passivation layers are provided at each contact interface of the doped layer to achieve interface optimization, while ensuring the gradual doping gradient of the doped layer. Furthermore, the multilayer passivation layers of the aforementioned passivation contact structure 20, including the passivation layers of the inner passivation contact units and the outer surface passivation layer 31, are designed with a progressively decreasing thickness and progressively increasing porosity from the inside out. That is, relatively thin passivation layers are configured with relatively large porosity, and relatively thick passivation layers are configured with relatively small porosity. These different passivation layers are arranged between different layers along the stacking direction to optimize the doping performance of each doped layer and the inner expansion layer on the surface of the substrate layer 10, thereby taking into account both the overall optical and electrical performance of the passivation contact structure 20.

[0038] It is known that the greater the thickness of the passivation layer, the stronger its ability to form saturated dangling bonds, and the better the passivation effect. Porosity refers to the percentage of the pore volume inside a material to the total volume of the material in its natural state. Therefore, the greater the porosity of the passivation layer, the greater the proportion of the pore area in the entire passivation layer, the weaker its barrier to impurity atoms, and the less impurity atoms accumulate at the interface.

[0039] like Figures 1 to 3 As shown, this disclosure uses an example with two passivated contact units for specific illustration.

[0040] The passivation contact structure 20 of the solar cell disclosed herein includes: a first passivation contact unit 1, a second passivation contact unit 2, and a surface passivation layer 31. The first passivation contact unit 1 is adapted to be formed on a substrate layer 10. The first passivation contact unit 1 includes a first passivation layer 11 and a first doped layer 12, with the first passivation layer 11 disposed relatively close to the substrate layer 10. The second passivation contact unit 2 is formed on the side of the first passivation contact unit 1 that is relatively far away from the substrate layer 10. The second passivation contact unit 2 includes a second passivation layer 21 and a second doped layer 22, with the second passivation layer 21 disposed relatively close to the first passivation contact unit 1. The surface passivation layer 31 is formed on the side of the second passivation contact unit 2 that is relatively far away from the substrate layer 10. The thicknesses of the first passivation layer 11, the second passivation layer 21, and the surface passivation layer 31 decrease sequentially, and the porosities of the first passivation layer 11, the second passivation layer 21, and the surface passivation layer 31 increase sequentially.

[0041] Specifically, the passivation contact structure 20 is configured with two passivation contact units and an outermost surface passivation layer 31, that is, including three passivation layers and two doped layers between adjacent passivation layers. Specifically, this disclosure first forms two doped layers with different doping concentrations through the second passivation layer 21 in the direction of dopant atom diffusion from the outside to the inside, so as to balance the improvement of contact performance and the reduction of parasitic absorption. For example, the second doped layer 22 with a higher doping concentration on the outside directly contacts the external electrode paste, and the low contact resistance helps to ensure electrical performance; while the first doped layer 12 on the inside, which is relatively close to the substrate layer 10, has a lower doping concentration and less parasitic absorption, which helps to ensure optical performance.

[0042] Based on this, this disclosure provides passivation layers on the upper and lower interfaces of each of the aforementioned doped layers. For example, the first passivation layer 11 optimizes the passivation effect at the contact interface between the first doped layer 12 and the substrate layer 10, the second passivation layer 21 optimizes the passivation effect at the contact interface between the first doped layer 12 and the second doped layer 22, and the surface passivation layer 31 optimizes the passivation effect on the outer surface of the second doped layer 22 on the outermost side. That is, according to the design requirements of the doped layer, passivation layers are provided at each contact interface of the doped layer to achieve interface optimization, while ensuring the gradual doping gradient of the doped layer. Furthermore, the three passivation layers of the aforementioned passivated contact structure 20 are designed with decreasing thickness and increasing porosity from the inside to the outside. That is, relatively thin passivation layers are configured with relatively large porosity, and relatively thick passivation layers are configured with relatively small porosity. These different passivation layers are set between different layers along the stacking direction to optimize the doping performance of the second doped layer 22, the first doped layer 12, and the inner expansion layer on the surface of the substrate layer 10, thereby taking into account both the overall optical and electrical performance of the passivated contact structure 20.

[0043] It is known that the greater the thickness of the passivation layer, the stronger its ability to form saturated dangling bonds, and the better the passivation effect. Porosity refers to the percentage of the pore volume inside a material to the total volume of the material in its natural state. Therefore, the greater the porosity of the passivation layer, the greater the proportion of the pore area in the entire passivation layer, the weaker its barrier to impurity atoms, and the less impurity atoms accumulate at the interface.

[0044] Specifically, the first passivation layer 11, which is closest to the substrate layer 10 among the three passivation layers, mainly determines the passivation effect at the interface between the first passivation layer 11 and the substrate layer 10 and the first doped layer 12. This first passivation layer 11 is designed to be the thickest and have the smallest porosity. On the one hand, the thickest thickness ensures the best passivation effect at the interface between the first doped layer 12 and the substrate layer 10, preventing a large number of carriers in the substrate layer 10 from recombining at the interface where they are first output. On the other hand, the first passivation layer 11 also needs to have a certain porosity, mainly to allow a small number of impurity atoms to expand into the substrate layer 10, thereby constructing a gentle gradient doping and enhancing the field passivation effect. At the same time, it prevents a large number of impurity atoms from accumulating at the interface of the first passivation layer 11, which would damage the interface passivation. In addition, the smaller porosity also helps a small number of metal particles to enter the substrate layer 10 during the subsequent sintering process, improving the contact performance of the battery without exacerbating the increase in contact recombination. Secondly, the second passivation layer 21, located between the first doped layer 12 and the second doped layer 22 in the three passivation layers, mainly serves as a barrier layer for atomic diffusion and a buffer layer for metal particles to embed into the inner first doped layer 12 and the base layer 10 during sintering. Its thickness and porosity are moderate. This is because if the thickness is too thick and the porosity is too small, it will hinder the inward diffusion of impurity atoms and the embedding of metal particles, resulting in insufficient inward diffusion, weak field passivation effect, and will also affect the collection performance of subsequent metal electrodes for charge carriers. If the thickness is too thin and the porosity is too large, it will not be able to effectively block the inward diffusion of impurity atoms, and impurity atoms will easily diffuse and accumulate at the interface, resulting in a decrease in the interface passivation effect. In addition, it will also cause a large number of metal particles to burn through the first passivation layer 11 and enter the base layer 10 during subsequent sintering, narrowing the window. The first passivation layer 11 and the second passivation layer 21 mentioned above are both internal interface passivation layers, while the surface passivation layer 31 serves as an external passivation layer to passivate the outermost surface. That is, a surface passivation layer 31 is set on the surface of the second doped layer 22 as an auxiliary control structure for the second passivation layer 21, further controlling the diffusion degree of impurity atoms and the sintering embedding depth of metal particles. It filters out some ineffective impurity atoms and metal particles from the outer surface, expanding the matching window. The second doped layer 22 and the surface doped layer make the matching space of the overall slurry larger than that of a single passivation layer, and the thickness of the overall doped layer can be further reduced, which is beneficial to the improvement of the optical performance of the battery.

[0045] Of course, in other embodiments, the thickness gradient of the first passivation layer 11, the second passivation layer 21, and the surface passivation layer 31 can also be limited individually, that is, the thickness of the first passivation layer 11, the second passivation layer 21, and the surface passivation layer 31 gradually decreases, but the porosity is not limited. Alternatively, the porosity gradient can be limited individually, that is, the porosity of the first passivation layer 11, the second passivation layer 21, and the surface passivation layer 31 gradually increases, but the thickness is not limited.

[0046] In some embodiments, the thickness of the first passivation layer 11 is set to a range of 2~5nm, such as 2nm, 2.5nm, 3nm, 3.5nm, 4nm, 4.5nm, 5nm, etc.; the thickness of the second passivation layer 21 is set to a range of 0.2~2nm, such as 0.2nm, 0.5nm, 1nm, 1.2nm, 1.5nm, 2nm, etc.; and the thickness of the surface passivation layer 31 is less than 0.2nm, such as 0.05nm, 0.1nm, 0.15nm, 0.2nm, etc. Within this thickness range, each passivation layer can achieve a balance between electrical and optical performance to the greatest extent, optimizing the overall passivation contact performance of the battery.

[0047] In some embodiments, such as Figure 1 As shown, the first passivation layer 11 has a plurality of first pores 111, the second passivation layer 21 has a plurality of second pores 211, and the surface passivation layer 31 has a plurality of surface pores 311; the lateral dimensions of the first pores 111, the second pores 211, and the surface pores 311 increase sequentially.

[0048] In other words, the porosity of each passivation layer is controlled by designing the lateral dimensions of the pores in each passivation layer. This method offers high visualization, simple and convenient control, and a large control window. In this disclosure, the pores can be through-holes penetrating the passivation layer, blind holes extending to a local thickness of the passivation layer, or partially formed as through-holes and partially as blind holes. The specific form is not strictly limited, as long as it can achieve differentiation in porosity.

[0049] Of course, in other embodiments, the density or depth of the pores in each passivation layer can also be controlled by designing them.

[0050] Based on the above, in some embodiments, the lateral dimension of the surface pores 311 is set to be less than 0.5 μm, such as 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, or 0.45 μm. That is, the maximum value of the surface pore 311 with the largest lateral dimension among the first pore 111, the second pore 211, and the surface pore 311 is limited. For example, if the lateral dimension of the surface pore 311 is 0.4 μm, then the lateral dimension of the second pore 211 is set to 0.2 μm, and the lateral dimension of the first pore 111 is set to 0.1 μm. This maximum value of 0.5 μm ensures that the vast majority of doped atoms cannot pass through, thus ensuring sufficient blocking effect of the three passivation layers while achieving the maximum relative permeability of the outermost layer.

[0051] Based on the above solution, in some embodiments, such as Figure 2 As shown, the passivation contact structure 20 of the solar cell disclosed herein includes a contact area A and a non-contact area B. An electrode structure is suitable for being disposed on the contact area A. In the same passivation layer, the porosity of the contact area A is greater than that of the non-contact area B. Furthermore, in the stacking direction from the surface of the substrate layer 10 outward, the porosity of the multiple contact areas A increases sequentially, and the porosity of the multiple non-contact areas B increases sequentially.

[0052] That is, the first passivation layer 11 includes a first contact area and a first non-contact area, the second passivation layer 21 includes a second contact area and a second non-contact area, and the surface passivation layer 31 includes a surface contact area and a surface non-contact area. The porosity of the first contact area is greater than that of the first non-contact area, the porosity of the second contact area is greater than that of the second non-contact area, and the porosity of the surface contact area is greater than that of the surface non-contact area.

[0053] Specifically, for the contact region A, the priority is given to carrier collection performance, while for the non-contact region B, the priority is given to passivation performance. Therefore, the porosity of the pores in the contact region A is set to be greater than that in the non-contact region B. On the one hand, setting a larger porosity in the contact region A is beneficial for metal particles to penetrate the entire doped layer, thereby achieving the purpose of effectively collecting carriers. On the other hand, the smaller porosity in the non-contact region B allows impurity diffusion atoms to penetrate, but it cannot effectively allow metal particles to penetrate.

[0054] Similarly, porosity can be achieved through different pore densities, pore sizes, or pore depths. This disclosure uses the lateral dimension of the pores, i.e., the pore size, as an example for illustration.

[0055] In some embodiments, the lateral dimension of the pores located in the contact area A is greater than the lateral dimension of the pores located in the non-contact area B; and in the stacking direction outward from the surface of the substrate layer 10, the lateral dimensions of the pores in the plurality of contact areas A increase sequentially, and the lateral dimensions of the pores in the plurality of non-contact areas B increase sequentially.

[0056] First, the lateral dimension A1 of the first pore 111 located in the first contact area is greater than the lateral dimension B1 of the first pore 111 located in the first non-contact area; the lateral dimension A2 of the second pore 211 located in the second contact area is greater than the lateral dimension B2 of the second pore 211 located in the second non-contact area; and the lateral dimension A3 of the surface pore 311 located in the surface contact area is greater than the lateral dimension B3 of the surface pore 311 located in the surface non-contact area. Adjusting the size of the pores in different regions of the same passivation layer to control the porosity is a simple and clear method, highly operable and visually appealing, with a large control window.

[0057] Secondly, the porosity of the contact areas A in different passivation layers can also be set to be different, with the porosity of the first contact area, the second contact area, and the surface contact area increasing sequentially. For example, taking the lateral dimension of the pores as an example, the lateral dimension A1 of the first pore in the first contact area is smaller than the lateral dimension A2 of the second pore 211 in the second contact area, and the lateral dimension A2 of the second pore 211 in the second contact area is smaller than the lateral dimension A3 of the surface pore 311 in the surface contact area. Setting the size of the first pore 111 in the first contact area to be the smallest effectively prevents excessive metal particles from burning through into the substrate layer 10, ensuring the passivation quality of the core interface. The pores in the second contact area and the surface contact area are relatively large, allowing metal particles to penetrate the first doped layer 12 and the second doped layer 22, thereby improving the carrier collection performance of the metal electrode for the doped layer.

[0058] Of course, the porosity of the non-contact areas B in different passivation layers can also be set differently, with the porosity of the first non-contact area, the second non-contact area, and the surface non-contact area increasing sequentially. Taking the lateral dimension of the pores as an example, the lateral dimension B1 of the first pore 111 located in the first non-contact area is smaller than the lateral dimension B2 of the second pore 211 located in the second non-contact area, and the lateral dimension B2 of the second pore 211 located in the second non-contact area is smaller than the lateral dimension B3 of the surface pore 311 located in the surface non-contact area.

[0059] Of course, the porosity can also be differentiated for one or two of the first passivation layer 11, the second passivation layer 21, and the surface passivation layer 31.

[0060] In some embodiments, the thickness of the plurality of doped layers increases sequentially in the stacking direction outward from the surface of the substrate layer 10. Taking two doped layers as an example, that is, the thickness of the first doped layer 12 is less than the thickness of the second doped layer 22.

[0061] It is known that the greater the thickness of the doped layer, the more doped atoms there are, and the more severe the parasitic absorption, but the better the contact performance. Therefore, this disclosure sets the thickness of the second doped layer 22, which is in direct contact with the metal electrode, to be relatively thick to ensure contact performance; correspondingly, the thickness of the first doped layer 12, which is not in contact with the metal electrode, is designed to be relatively small, thereby reducing the overall thickness of the doped layer structure, that is, reducing parasitic absorption within the doped layer, and ensuring photoelectric conversion efficiency and carrier collection.

[0062] In one embodiment, multiple doped layers have the same doping type. That is, the first doped layer 12 and the second doped layer 22 have the same doping type. In other words, the design of multiple doped layers and multiple passivation layers is integrated into the passivation contact structure 20 with the same doping type, which helps to optimize the direct application of the passivation contact structure 20 in various types of batteries.

[0063] In one embodiment, in the stacking direction outward from the surface of the substrate layer 10, the doping concentration of the multiple doped layers increases sequentially; and the doping concentration within any doped layer gradually increases. Similarly, taking two doped layers as an example, the doping concentration of the first doped layer 12 is less than the doping concentration of the second doped layer 22; and in the direction from the second doped layer 22 to the first doped layer 12, the doping concentration within the first doped layer 12 gradually decreases, and the doping concentration within the second doped layer 22 gradually decreases.

[0064] That is, with the overall doping concentration of the first doped layer 12 being less than that of the second doped layer 22, and taking into account both contact performance and parasitic absorption, each doped layer itself is also set to have a gradual gradient change in doping concentration from the outside to the inside, further optimizing contact performance and optical performance.

[0065] like Figure 3 As shown, in some embodiments, the passivation contact structure 20 of the solar cell further includes a first passivation antireflection layer 4 formed on the side of the surface passivation layer 31 that is relatively far from the substrate layer 10. The first passivation antireflection layer 4 may be one or more of intrinsic amorphous silicon, aluminum oxide, and silicon nitride, reducing light reflection on the surface of the passivation contact structure 20 and also helping to achieve surface protection of the passivation contact structure 20.

[0066] like Figure 4As shown, this disclosure also provides a solar cell, including: a substrate layer 10, a first passivation contact structure 201 and a second passivation contact structure 202, a first electrode 301 and a second electrode 302, wherein the first passivation contact structure 201 and the second passivation contact structure 202 are respectively formed on opposite side surfaces of the substrate layer 10, or alternately formed on one side surface of the substrate layer 10, and the doping types of the first passivation contact structure 201 and the second passivation contact structure 202 are opposite; at least one of the first passivation contact structure 201 and the second passivation contact structure 202 adopts the above-mentioned passivation contact structure 20; the first electrode 301 is disposed on the first passivation contact structure 201, and the second electrode 302 is disposed on the second passivation contact structure 202.

[0067] That is, the passivation contact structure 20 described above can be applied to various battery structures such as conventional TOPCon batteries, HJT batteries, and back contact batteries. If the solar cell is a TOPCon battery or an HJT battery, the first passivation contact structure 201 and the second passivation contact structure 202 are respectively disposed on the light-receiving surface 101 and the back-lighting surface 102 of the substrate layer 10. If the solar cell is a back contact battery, the first passivation contact structure 201 and the second passivation contact structure 202 are alternately formed on the back-lighting surface 102. The two passivation contact structures with different doping types in the solar cell can be either the multi-layer gradient design passivation contact structure 20 described above or a conventional passivation contact structure, or both can be the multi-layer gradient design passivation contact structure 20 described above, to further optimize the overall passivation contact performance of the battery and thus improve the power generation efficiency.

[0068] Of course, when the battery is a back-contact battery, a second passivation antireflection layer 40 can be provided on the light-receiving surface 101.

[0069] Further functional descriptions of the above structures are the same as those of the corresponding embodiments described above, and will not be repeated here.

[0070] Although embodiments of the present disclosure have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present disclosure, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A passivated contact structure for a solar cell, characterized in that, include: Multiple passivated contact units are stacked sequentially on the substrate layer; The plurality of passivation contact units include a first passivation contact unit to an Nth passivation contact unit, where N is an integer greater than or equal to 2; each of the passivation contact units includes a passivation layer and a doped layer stacked together, wherein the passivation layer is disposed relatively close to the substrate layer; in the stacking direction outward from the surface of the substrate layer, the thickness of the plurality of passivation layers decreases sequentially, and / or the porosity of the plurality of passivation layers increases sequentially; A surface passivation layer is formed on the surface of the Nth passivation contact unit that is relatively far from the substrate layer; the thickness of the surface passivation layer is less than the thickness of the Nth passivation layer, and / or the porosity of the surface passivation layer is greater than the porosity of the Nth passivation layer.

2. The passivated contact structure of the solar cell according to claim 1, characterized in that, The plurality of passivated contact units include: A first passivation contact unit is adapted to be formed on a substrate layer; the first passivation contact unit includes a first passivation layer and a first doped layer, wherein the first passivation layer is disposed relatively close to the substrate layer; A second passivation contact unit is formed on the side of the first passivation contact unit that is relatively far away from the substrate layer; the second passivation contact unit includes a second passivation layer and a second doped layer, the second passivation layer being disposed relatively close to the first passivation contact unit; The thicknesses of the first passivation layer, the second passivation layer, and the surface passivation layer decrease sequentially, and / or the porosity of the first passivation layer, the second passivation layer, and the surface passivation layer increases sequentially.

3. The passivated contact structure of the solar cell according to claim 2, characterized in that, The thickness of the first passivation layer ranges from 2 to 5 nm, the thickness of the second passivation layer ranges from 0.2 to 2 nm, and the thickness of the surface passivation layer is less than 0.2 nm.

4. The passivated contact structure of the solar cell according to claim 2, characterized in that, The first passivation layer has a plurality of first pores, the second passivation layer has a plurality of second pores, and the surface passivation layer has a plurality of surface pores; the lateral dimensions of the first pores, the second pores, and the surface pores increase sequentially.

5. The passivated contact structure of the solar cell according to claim 4, characterized in that, The lateral dimension of the surface pores is less than 0.5 μm.

6. The passivated contact structure of the solar cell according to claim 1, characterized in that, The passivated contact structure includes a contact area and a non-contact area, and an electrode structure is adapted to be disposed on the contact area; in the same passivation layer, the porosity of the contact area is greater than that of the non-contact area; and in the stacking direction from the surface of the substrate layer outward, the porosity of the multiple contact areas increases sequentially, and the porosity of the multiple non-contact areas increases sequentially.

7. The passivated contact structure of the solar cell according to claim 6, characterized in that, The lateral dimension of the pores located in the contact area is greater than that of the pores located in the non-contact area; and in the stacking direction outward from the surface of the substrate layer, the lateral dimensions of the pores in the plurality of contact areas increase sequentially, and the lateral dimensions of the pores in the plurality of non-contact areas increase sequentially.

8. The passivated contact structure of the solar cell according to claim 1, characterized in that, In the stacking direction from the surface of the substrate layer outward, the thickness of the plurality of doped layers increases sequentially.

9. The passivated contact structure of the solar cell according to claim 1, characterized in that, The doping types of the multiple doped layers are the same.

10. The passivated contact structure of the solar cell according to claim 1, characterized in that, In the stacking direction from the surface of the substrate layer outward, the doping concentration of the plurality of doped layers increases sequentially; and the doping concentration inside any one of the doped layers gradually increases.

11. The passivated contact structure of the solar cell according to claim 1, characterized in that, Also includes: A first passivation anti-reflection layer is formed on the side of the surface passivation layer that is relatively far from the base layer.

12. A solar cell, characterized in that, include: basal layer; The first passivation contact structure and the second passivation contact structure are respectively formed on opposite two sides of the substrate layer, or alternately formed on one side of the substrate layer; the doping types of the first passivation contact structure and the second passivation contact structure are opposite; at least one of the first passivation contact structure and the second passivation contact structure adopts the passivation contact structure according to any one of claims 1 to 9. A first electrode and a second electrode, wherein the first electrode is disposed on the first passivation contact structure and the second electrode is disposed on the second passivation contact structure.

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