Passivation contact structure of solar cell, solar cell, assembly and system
By employing a multilayer doped structure in solar cells, the combination of small-sized dopant elements blocking boron diffusion and high-concentration doped layers solves the problem of thin film quality degradation caused by boron impurity enrichment and diffusion, thereby improving the performance of the passivated contact structure and cell efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-12
- Publication Date
- 2026-03-13
Smart Images
Figure CN121665735A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of photovoltaic technology, and in particular relates to a passivated contact structure for a solar cell, a solar cell, a module, and a system. Background Technology
[0002] In recent years, passivation contact technology has attracted much attention due to its ability to effectively avoid direct contact between the silicon substrate and the metal electrode. This technology, by stacking an ultrathin tunneling oxide layer and a doped polycrystalline silicon layer on crystalline silicon, can significantly reduce carrier recombination in the metal-semiconductor contact region while exhibiting excellent contact performance, thereby greatly improving the efficiency of solar cells. However, current passivation contact technology still faces many challenges. The main problems include the enrichment of boron impurities in SiOx and the degradation of SiOx film quality caused by boron diffusion. These factors lead to difficult-to-passivate BO defects, pinholes, and interface defects. Furthermore, the smaller atomic radius of boron compared to phosphorus results in greater strain caused by boron atoms, leading to the formation of more defects in the oxide interlayer. Summary of the Invention
[0003] This application provides a solar cell designed to address the enrichment of boron impurities in SiOx and the degradation of SiOx film quality caused by boron diffusion. These factors lead to difficult-to-passivate BO defects, pinholes, and interface defects. Furthermore, the smaller atomic radius of boron compared to phosphorus results in greater strain induced by boron atoms, leading to the formation of more defects in the oxide interlayer.
[0004] In a first aspect, this application provides a passivation contact structure for a solar cell, comprising: a silicon substrate; a first dielectric layer disposed on the silicon substrate; a first doped layer disposed on the first dielectric layer; and a second doped layer disposed on the first doped layer; wherein the first doped layer is doped with a first doping element; the atomic size of the first doping element is smaller than the atomic size of silicon atoms in the first doped layer; the second doped layer is doped with the first doping element, and the concentration of the first doping element in the second doped layer is smaller than the concentration of the first doping element in the first doped layer.
[0005] Optionally, the first doping element includes at least one of nitrogen, carbon, and fluorine.
[0006] Optionally, a second dielectric layer is disposed between the first doped layer and the second doped layer.
[0007] Optionally, the first doped layer and the second doped layer contain the same second doping element, which is one of boron, aluminum, and gallium. Optionally, the doping concentration of the second doping element in the first doped layer is lower than the doping concentration of the second doping element in the second doped layer.
[0008] Optionally, the first doped layer is at least one of a polycrystalline silicon layer, a microcrystalline silicon layer, or an amorphous silicon layer.
[0009] Optionally, the second doped layer is at least one of a polycrystalline silicon layer, a microcrystalline silicon layer, or an amorphous silicon layer.
[0010] Optionally, the doping concentration of the second dopant element in the first doped layer is 5 × 10¹. 5 cm - ³~5×10 19 cm - ³.
[0011] Optionally, the doping concentration of the second doped element in the second doped layer is 5 × 10⁻⁶. 18 ~2×10 20 cm - ³.
[0012] Optionally, the thickness of the first dielectric layer is 1 nm to 5 nm.
[0013] Optionally, the thickness of the first doped layer is 3 nm to 100 nm.
[0014] Optionally, the first doping element is doped between a plurality of silicon atoms within the first doped layer.
[0015] Optionally, the doping concentration of the first doped element in the first doped layer is 0.5 at% to 25 at%.
[0016] Optionally, the thickness of the second doped layer is 10 nm to 1000 nm.
[0017] Optionally, the thickness of the first doped layer is less than the thickness of the second doped layer.
[0018] Optionally, the first dielectric layer and the second dielectric layer are one or more of the following: oxide layer, nitride layer, oxynitride layer, carbide layer, and amorphous silicon layer.
[0019] Optionally, the first doping element is doped between silicon atoms in the second dielectric layer.
[0020] This application involves doping a first doping element into a first doping layer. The atomic size of the first doping element is smaller than that of silicon atoms in the first doping layer. The first doping element fills the spaces between silicon atoms in the first doping layer. Utilizing the strong boron blocking ability of the first doping element atoms, a barrier is established within the first doping layer to prevent boron atoms in the second doping layer from diffusing to the first dielectric layer. By controlling the distribution of the first doping element, boron diffusion is controlled, effectively reducing boron enrichment in the first dielectric layer, reducing interface defects, and significantly improving the performance of the passivation contact structure. Furthermore, the second doping layer, as a lateral conductive layer, is used to ensure passivation quality and battery conductivity. It has a high electromobility and can effectively collect and transport charge carriers.
[0021] Secondly, a solar cell includes the passivated contact structure of the aforementioned solar cell. The technical effects of this application are the same as those of the passivated contact structure of the aforementioned solar cell, and will not be repeated here.
[0022] Thirdly, a solar cell module includes the aforementioned solar cell. The technical effects of this application are the same as those of the aforementioned solar cell, and will not be repeated here.
[0023] Fourthly, a photovoltaic system includes the aforementioned solar cell module. The technical effects of this application are the same as those of the aforementioned solar cell module, and will not be repeated here. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the passivation contact structure of the first type of solar cell provided in this application; Figure 2 This is a schematic diagram of the passivation contact structure of the second type of solar cell provided in the current application; Figure 3 This is a schematic diagram of the structure of a solar cell provided in the present application; Figure 4 This is a schematic diagram of another type of solar cell provided in the current application.
[0025] Explanation of reference numerals in the attached figures: 100, Silicon substrate; 200, First dielectric layer; 300, First doped layer; 400, Second doped layer; 500, Second dielectric layer; 600, Passivation layer; 700, Electrode structure; 800, Third doped layer; 900, Third dielectric layer. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.
[0027] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.
[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.
[0029] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0030] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0031] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.
[0032] like Figure 1 and Figure 2 As shown in this embodiment, a passivation contact structure for a solar cell includes a silicon substrate 100. Typically, the silicon substrate is a sheet-like structure. The side that absorbs light energy and converts it into electrical energy is called the light-absorbing surface or front side, and the other side is called the back side. The front and back sides of the silicon substrate are arranged opposite each other. The silicon substrate is substantially rectangular, but it can be, for example, a square or another type of rectangle, and can have standard corners, cut corners, or rounded corners, depending on actual production needs, and is not specifically limited here. In this embodiment, the silicon substrate 100 is a P-type silicon wafer. It is understood that in other embodiments, the silicon substrate 100 can also be other types of silicon wafers.
[0033] In this application, the type of solar cell can be a back contact cell, such as an IBC cell; or other cell types, such as PERC cells, HJT cells, or TOPCon cells, etc. This application does not limit this.
[0034] Further, a first dielectric layer 200 is disposed on the silicon substrate 100, a first doped layer 300 is disposed on the first dielectric layer 200, and a second doped layer 400 is disposed on the first doped layer 300. Preferably, the first doped layer 300 is at least one of a polycrystalline silicon layer, a microcrystalline silicon layer, or an amorphous silicon layer. Similarly, the second doped layer 400 is at least one of a polycrystalline silicon layer, a microcrystalline silicon layer, or an amorphous silicon layer, and the first doped layer 300 and the second doped layer 400 are preferably polycrystalline silicon layers. The first doped layer 300 and the second doped layer 400 contain the same second doping element, which, when doped into the lattice of the silicon substrate 100, replaces the positions of silicon atoms. Because they have one less valence electron than silicon, a "vacancy" is created in the covalent bond; this vacancy is a hole. The role of the second doping element is to introduce a "hole" as a majority carrier in the semiconductor (such as silicon), thereby forming p-type conductivity. For example, the second doping element is one of boron, aluminum, or gallium. Of course, the second dopant element can also be a group III element or other element in the periodic table, and this application does not impose any restrictions on this.
[0035] In some embodiments, such as Figure 1 As shown, the coverage areas of the first doped layer 300 and the second doped layer 400 on the surface of the solar cell can be the same or different, for example, as shown in the figure. Figure 1 As shown, the coverage area of the second doped layer 400 on one surface of the solar cell is smaller than the coverage area of the first doped layer 300 on one surface of the solar cell, or as... Figure 2 The coverage area of the second doped layer 400 on one surface of the solar cell is equal to the coverage area of the first doped layer 300 on one surface of the solar cell. By reasonably setting the coverage area of the second doped layer 400, a good balance between enhancing lateral conductivity and reducing series resistance can be achieved.
[0036] It should be noted that, for ease of explanation, boron can be used as an example of the second doping element. It is understood that the boron element mentioned below is only an example for the purpose of illustrative explanation and is not limited thereto. Other elements in the second doping element can also be applied.
[0037] like Figure 3As shown, exemplarily, in one embodiment, the solar cell is a TOPCon cell, based on a P-type silicon wafer as the silicon substrate 100. A third doped layer 800 is formed on the front side of the silicon substrate 100 using a full-area n+ type phosphorus emitter. A third dielectric layer 900 can also be disposed between the front side of the silicon substrate 100 and the third doped layer 800, and the third dielectric layer 900 is used to passivate the front side of the silicon substrate 100. The back side of the silicon substrate 100 typically uses a p+ type doped boron-doped polycrystalline silicon layer. Specifically, an ultrathin silicon oxide layer is first grown on the back side of the silicon substrate 100 to form a first dielectric layer 200, and then a boron-doped P+ type polycrystalline silicon layer is deposited to form a first doped layer 300. The P+ polycrystalline silicon layer and the p-type substrate form a P+ / p high-low junction at the contact interface. Its built-in electric field can effectively reflect electrons (minority carriers) towards the front side, while attracting and collecting holes, greatly improving the hole collection efficiency on the back side and preventing electrons (minority carriers) from reaching the back side for recombination.
[0038] In some embodiments, the third dielectric layer 900 and the first dielectric layer 200 are tunneling oxide layers, typically contacting the silicon substrate 100 on one side and an adjacent doped layer on the other. The tunneling oxide layer is typically composed of silicon dioxide (SiO2) and is very thin, usually between 1-2 nm. Tunneling occurs in the tunneling oxide layer, allowing minority carriers to be transported from the silicon substrate 100 to the adjacent doped layer. Although very thin, the tunneling oxide layer provides additional insulating properties, preventing unwanted charge leakage between different regions.
[0039] The doped layer can be in direct contact with the tunneling oxide layer, or it can be in indirect contact with the tunneling oxide layer through other functional layers (i.e., other functional layers are set between the tunneling oxide layer and the doped layer), and there is no limitation here.
[0040] like Figure 4 As shown, exemplarily, in another embodiment, the solar cell is a back-contact cell. An n-type doped region and a p-type doped region are alternately spaced on the back side of a silicon substrate 100. Exemplarily, a phosphorus-doped layer is formed in the n-type doped region to constitute a third doped layer 800. A third dielectric layer 900 is formed between the surface of the silicon substrate 100 in the n-type doped region and the third doped layer 800 to passivate the surface of the silicon substrate 100 in the n-type doped region. A dielectric layer and a boron-doped layer are formed in the p-type doped region. The dielectric layer in the p-type doped region forms the first dielectric layer 200 of this application, and the boron-doped layer in the p-type doped region forms the first doped layer 300 of this application.
[0041] The first dielectric layer 200 and the first doped layer 300 together constitute a "passivated contact" structure. This structure can achieve extremely high surface passivation quality, significantly reduce carrier recombination on the back surface, and achieve extremely high carrier selectivity, thereby bringing high conversion efficiency, high bifaciality, and low attenuation performance.
[0042] In traditional passivated contact structures, the preparation of the doped layer requires high-temperature sintering. During this process, boron impurities within the doped layer tend to accumulate in SiOx, and boron diffusion causes quality degradation of the SiOx film. These factors lead to difficult-to-passivate BO defects, pinholes, and interface defects. These defects become electron-hole recombination centers, resulting in performance degradation. Increased carrier recombination directly reduces the minority carrier lifetime of the battery, severely limiting the passivation effect of the passivated contact structure and the photoelectric conversion efficiency of the battery.
[0043] Based on this, a second doped layer 400 is disposed on the first doped layer 300 in this application. The second doped layer 400 and the first doped layer 300 are doped with the same element. For example, both the second doped layer 400 and the first doped layer 300 are doped with boron. The second doped layer 400 serves as a lateral conductive layer to ensure passivation quality and battery conductivity. Specifically, the first doped layer 300 is doped with a first doping element. Exemplarily, the first doping element includes at least one of nitrogen, carbon, and fluorine. The atomic size of the first doping element is smaller than the atomic size of silicon atoms in the first doped layer 300. In this way, the first dopant element can be doped between silicon atoms in the first doped layer 300, allowing it to enter the interstitial spaces between silicon atoms in the polycrystalline silicon, thereby preventing further diffusion of boron. The first dopant element in the first doped layer 300 can significantly reduce the crystallinity of the thin film and the boron activation rate, and reduce the generation of interface defects. By utilizing the strong boron blocking ability of the first dopant element, precise control of boron diffusion behavior can be achieved, significantly reducing the interface state density and effectively suppressing the generation of interface defects. This overcomes the shortcomings of traditional polycrystalline silicon layer preparation methods in the prior art, which have difficulty in effectively controlling the distribution of boron atoms.
[0044] This application employs a multi-layer doped system, and achieves boron diffusion control by regulating the distribution of the first doped element within the first doped layer 300. This effectively reduces boron enrichment in the tunneling layer, reduces interface defects, and significantly improves the passivation performance of the solar cell. It solves the problem of SiOx film quality degradation caused by boron impurity enrichment and boron diffusion in the prior art.
[0045] Understandably, the multilayer doped structure of this application can also be applied to the n-type doped region of a solar cell to block the diffusion of phosphorus elements within the dielectric layer. Specifically, a first dielectric layer 200, a first doped layer 300, and a second doped layer 400 are sequentially disposed within the n-type doped region. For example, the first doped layer 300 is a nitrogen- and phosphorus-doped layer, and the second doped layer 400 is a phosphorus-doped layer. After nitrogen is doped into the first doped layer 300, a barrier layer is formed, preventing the diffusion of phosphorus elements from the second doped layer 400 into the first doped layer 300 and the first dielectric layer 200, thereby reducing interface defects in the passivation contact structure within the n-type doped region.
[0046] Understandably, a passivation layer 600 can also be disposed on the outer side of the second doped layer 400 to form protection for the multilayer doped layers. When the electrode structure 700 is subsequently disposed in the doped region, the electrode structure 700 needs to penetrate the passivation layer 600 to contact the second doped layer 400, thereby achieving carrier collection within the silicon substrate 100. Preferably, the depth of the electrode structure 700 penetrating the second doped layer 400 is less than the thickness of the second doped layer 400. This avoids the electrode structure 700 piercing the second doped layer 400, prevents damage to the first doped layer 300 and the first dielectric layer 200 structure below the second doped layer 400, and reduces the negative impact of the electrode structure on the passivation contact of the first doped layer 300 and the first dielectric layer 200 below the second doped layer 400. Preferably, the electrode structure 700 penetrates the second doped layer 400 to a depth of at least 1 / 2 of the thickness of the second doped layer 400. The depth of the electrode structure 700 is set within the above range to ensure efficient transport of majority carriers (such as electrons) while avoiding excessive penetration that would lead to an increase in interface defects in the first doped layer 300 and the first dielectric layer 200 below the second doped layer 400, thus achieving a dual balance between contact efficiency and structural stability.
[0047] In some embodiments, the thickness of the second doped layer 400 is greater than the thickness of the first doped layer 300. This ensures that the second doped layer 400 has sufficient lateral conductivity and, secondly, ensures sufficient penetration depth of the electrode structure metal to achieve low contact resistance, enabling efficient transport of majority carrier (such as holes) charge in this layer, reducing series resistance losses, and improving the output efficiency of the solar cell.
[0048] In some embodiments, a second dielectric layer 500 is disposed between the first doped layer 300 and the second doped layer 400. Thus, the first dielectric layer 200 and the first doped layer 300, the second dielectric layer 500 and the second doped layer 400 constitute a double-layer passivation contact structure, which can optimize the transport and passivation effect of the same type of charge carrier. Specifically, the first dielectric layer 200 can be used to form a stable oxide layer and achieve passivation of the silicon substrate 100. The first doped layer 300 can be lightly doped, which reduces the damage of the dopant to the silicon wafer surface lattice, thereby obtaining a lower interface state density and improving the chemical passivation effect. The second doped layer 400 can be heavily doped, and the heavily doped layer has excellent lateral conductivity, which can effectively conduct current to the electrode metal contact point, reducing resistance. Heavy doping ensures that a low-resistance ohmic contact can be formed with the metal electrode. Furthermore, the second dielectric layer 500 disposed between the first doped layer 300 and the second doped layer 400 can block the transmission of stress and prevent the accumulated stress from damaging the silicon wafer interface, thereby further improving the passivation quality.
[0049] In some embodiments, the first dopant element is doped between silicon atoms within the second dielectric layer 500. Since the second dielectric layer 500 is disposed between the first doped layer 300 and the second doped layer 400, the second doped layer 400 has a high concentration of boron doping, and the first doped layer 300 has a low concentration of boron doping. The first dopant element is doped between silicon atoms within the second dielectric layer 500. The second dielectric layer 500 has a blocking effect on the diffusion of boron from the second doped layer 400 to the first doped layer 300, so that the boron element in the first doped layer 300 is kept at a low concentration of doping, thereby reducing the diffusion of boron element in the first doped layer 300 to the first dielectric layer 200.
[0050] In some embodiments, the doping concentration of the second dopant element in the first doped layer 300 is lower than that in the second doped layer 400. This differentiated arrangement of the second dopant elements in the first doped layer 300 and the second doped layer 400 enables functional separation between them. The low doping in the first doped layer 300 significantly reduces the interface state density, thereby improving the "chemical passivation" effect. The high doping in the second doped layer 400 provides efficient lateral current conduction and excellent metal contact. Furthermore, the first and second doped layers 400 establish a buffer diffusion mechanism through a gradient concentration field, significantly mitigating boron enrichment in the first dielectric layer 200.
[0051] Furthermore, the doping concentration of the second dopant element within the first doped layer 300 is 5 × 10¹ 5 cm - ³~5×10 19 cm -³. The doping concentration of the second doping element within the first doped layer 300 is within this range, which can reduce the diffusion of the second doping element within the first doped layer 300 into the first dielectric layer 200, thus preventing the degradation of the performance of the first dielectric layer 200.
[0052] Furthermore, the doping concentration of the second doped element within the second doped layer 400 is 5 × 10⁻⁶. 18 cm - ³~2×10 20 cm - ³. The doping concentration of the second doping element in the second doped layer 400 is within this range, and the second doped layer 400 can have a high electromobility, which can effectively collect and transport charge carriers.
[0053] In some embodiments, the thickness of the first dielectric layer 200 is 1 nm to 5 nm. Exemplarily, the thickness of the first dielectric layer 200 can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, etc., or any value from 1 nm to 5 nm; this application does not limit this. Within this range, the first dielectric layer 200 can form a good tunneling effect, and the first dielectric layer 200 can form stable chemical bonds with the silicon atoms of the silicon substrate 100, saturating these dangling bonds, thereby significantly reducing the interface state density.
[0054] In some embodiments, the thickness of the first doped layer 300 is 3 nm to 100 nm. Exemplarily, the thickness of the first doped layer 300 can be 3 nm, 10 nm, 30 nm, 40 nm, 70 nm, 100 nm, etc., or any value from 3 nm to 100 nm; this application does not limit this. The thickness of the first doped layer 300 within this range minimizes damage to the lattice of the underlying silicon wafer surface during the doping process, contributing to extremely low interface state density and optimal chemical passivation. Furthermore, the first doped layer 300 can form an effective electric field with the silicon substrate 100, achieving excellent field-effect passivation and blocking one type of charge carrier from reaching the interface.
[0055] In some embodiments, the doping concentration of the first dopant element in the first doped layer 300 is 0.5 at% to 25 at%. Within this range, the first dopant element in the first doped layer 300 can precisely control the boron diffusion depth, suppress defects, and mitigate the risk of boron enrichment in the first dielectric layer 200.
[0056] In some embodiments, the thickness of the second doped layer 400 is 10 nm to 1000 nm. Exemplarily, the thickness of the second doped layer 400 can be 10 nm, 80 nm, 100 nm, 400 nm, 700 nm, 1000 nm, etc., or any value between 10 nm and 1000 nm; this application does not limit this. With the thickness of the second doped layer 400 within this range, the second doped layer 400, as a lateral conductive layer, can ensure passivation quality and the conductivity of the battery. The high mobility characteristics of the second doped layer 400 enable efficient lateral transport of charge carriers, avoiding the current congestion effect caused by thin-layer structures.
[0057] The first dielectric layer 200 and the second dielectric layer 500 are tunneling layers, comprising one or more of the following: oxide layer, nitride layer, oxynitride layer, carbide layer, and amorphous silicon layer. It is understood that the specific structural arrangement of the first dielectric layer 200 and the second dielectric layer 500 includes, but is not limited to, the methods listed above. The dielectric layers are configured according to actual application needs, and no specific limitations are made here.
[0058] In some embodiments, the electrode structure 700 described above includes a positive electrode and a negative electrode. When the solar cell is a back-contact cell, both the positive and negative electrodes are arranged alternately on the back side of the solar cell. When the solar cell is a double-sided contact cell such as TOPCon, one of the positive and negative electrodes is located on the back side of the solar cell, and the other is located on the front side of the solar cell. Specifically, the electrode structure 700 is a fine grid of the solar cell. In some embodiments, the electrode structure 700 may also be the main grid of the solar cell.
[0059] In some embodiments, the passivation layer 600 is typically placed over the outermost functional layer, covering the top and sides of the other stacked functional layers to provide physical protection against surface damage, contamination, and chemical corrosion. Simultaneously, the passivation layer 600 reduces the defect state density on the semiconductor surface, decreases the surface recombination rate, and improves the quantum efficiency of the optoelectronic device. Preferably, the passivation layer 600 is composed of one or more of an oxide layer, a nitride layer, an oxide-oxygen nitride layer, a carbide layer, and an amorphous silicon layer. As examples of the invention, the passivation layer 600 can be made of a single material, a combination of multiple materials, or a combination of multiple layers of a single material with different refractive indices. It is understood that the specific structural arrangement of the passivation layer 600 includes, but is not limited to, the several arrangements listed above. The passivation layer 600 is configured according to actual usage needs and is not specifically limited here. The passivation layer 600 neutralizes dangling bonds on the surface of the textured region, effectively passivates defects in the textured region, and reduces recombination centers. For example, the passivation layer 600 can be composed of one or more layers selected from titanium dioxide, zinc oxide, silicon oxide, aluminum oxide, silicon nitride, and silicon oxynitride. Furthermore, the advantages of using one or more layers of these materials to form the passivation layer 600 are as follows: The titanium dioxide (TiO2) layer has a high refractive index (approximately 2.4%), which can serve as an anti-reflective layer and improve light absorption. The zinc oxide (ZnO) layer is a transparent conductive material that can simultaneously improve light transmittance and conductivity. Simultaneously, zinc oxide has a low refractive index (approximately 2.0%), which can reduce light reflection. The silicon dioxide (SiO2) layer has stable insulating properties, preventing charge leakage; its fabrication process is mature and easily prepared using mature processes such as thermal oxidation. The aluminum oxide (Al2O3) layer has a high breakdown voltage, enabling stable operation under high voltage. Simultaneously, aluminum oxide has excellent insulating properties, further improving device reliability. Specifically, the passivation layer 600 can be a titanium dioxide layer, a zinc oxide layer, a silicon oxide layer, an aluminum oxide layer, or a combination of a titanium dioxide layer and a zinc oxide layer, or a combination of a zinc oxide layer, a silicon oxide layer, and an aluminum oxide layer. It can also be any combination of at least two of the following: titanium dioxide layer, zinc oxide layer, silicon oxide layer, aluminum oxide layer, silicon nitride layer, and silicon oxynitride layer. No limitation is made here.
[0060] The electrode structure 700 penetrates the passivation layer 600 and contacts the doped layer beneath it. Specifically, the electrode structure 700 can be formed by drilling holes through the passivation layer 600, with the electrode structure 700 filling the holes and contacting the doped layer. In this case, a low-temperature base metal material can be used to achieve a non-burn-through metallization process. This process requires opening a predetermined area, i.e., removing the passivation layer 600 on the cell in a specific area, thereby forming an opening in the passivation layer 600. This opening exposes the doped layer beneath the passivation layer 600, and the electrode structure 700 can then pass through the opening to contact the doped layer, thus achieving the purpose of collecting photogenerated carriers. To balance cost, efficiency, and accuracy, embodiments of the invention can use laser film opening or mask etching to prepare the opening. The non-burn-through paste used in the electrode structure 700 includes at least one of silver, aluminum, and copper, reducing the cost of the paste while ensuring excellent conductivity.
[0061] In other embodiments, the electrode structure 700 may burn through the passivation layer 600 and contact the doped layer below it. In this case, the electrode structure 700 uses a burn-through paste that can penetrate or burn through the passivation layer 600 and contact the doped layer to establish a conductive channel. Burn-through pastes typically have high conductivity and good wettability, and can achieve good penetration during the firing process. Its components include at least one of silver and aluminum, thus ensuring that the burn-through paste has both burn-through characteristics and excellent conductivity.
[0062] In some embodiments, the second doped layer 400 is doped with a first dopant element, and the concentration of the first dopant element in the second doped layer 400 is less than the concentration of the first dopant element in the first doped layer 300. Preferably, the concentration of the first dopant element in the second doped layer 400 is less than 1 / 100 of the concentration of the first dopant element in the first doped layer 300, to avoid the first dopant element crowding out the internal lattice interstices of the second doped layer 400, affecting the high doping in the second doped layer 400, and ensuring the high mobility characteristics and low contact resistance of the second doped layer 400 to achieve efficient lateral transport of charge carriers.
[0063] In some embodiments, a solar cell includes the passivated contact structure of the solar cell described above. The technical effects of this application are the same as those of the passivated contact structure of the solar cell described above, and will not be repeated here.
[0064] In some embodiments, a solar cell module includes the solar cell described above. The technical effects of this application are the same as those of the solar cell described above, and will not be repeated here.
[0065] A photovoltaic system includes the aforementioned solar cell modules. In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants, and can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system grid as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.
[0066] In the description of this specification, the use of terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., refers to specific features, structures, materials, or characteristics described in connection with the embodiments or examples, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0067] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A passivated contact structure for a solar cell, characterized in that, include: Silicon substrate; A first dielectric layer disposed on the silicon substrate; A first doped layer disposed on the first dielectric layer; A second doped layer disposed on the first doped layer; The first doped layer is doped with a first doping element; The atomic size of the first dopant element is smaller than the atomic size of silicon atoms in the first doped layer; The second doped layer is doped with the first doping element, and the concentration of the first doping element in the second doped layer is less than the concentration of the first doping element in the first doped layer.
2. The passivated contact structure of the solar cell as described in claim 1, characterized in that, The first doping element includes at least one of nitrogen, carbon, and fluorine.
3. The passivated contact structure of the solar cell as described in claim 1, characterized in that, A second dielectric layer is disposed between the first doped layer and the second doped layer.
4. The passivated contact structure of the solar cell as described in claim 1, characterized in that, The first doped layer and the second doped layer contain the same second doping element, which is one of boron, aluminum, and gallium.
5. The passivated contact structure of the solar cell as described in claim 4, characterized in that, The doping concentration of the second doping element in the first doped layer is lower than that in the second doped layer.
6. The passivated contact structure of the solar cell as described in claim 4, characterized in that, The first doped layer is at least one of a polycrystalline silicon layer, a microcrystalline silicon layer, or an amorphous silicon layer.
7. The passivated contact structure of the solar cell as described in claim 4, characterized in that, The second doped layer is at least one of a polycrystalline silicon layer, a microcrystalline silicon layer, or an amorphous silicon layer.
8. The passivated contact structure of the solar cell as described in claim 5, characterized in that, The doping concentration of the second dopant element in the first doped layer is 5 × 10¹ 5 cm - ³~5×10 19 cm - ³.
9. The passivated contact structure of the solar cell as described in claim 5, characterized in that, The doping concentration of the second doped element in the second doped layer is 5 × 10⁻⁶. 18 ~2×10 20 cm - ³.
10. The passivated contact structure of the solar cell as described in claim 1, characterized in that, The thickness of the first dielectric layer is 1 nm to 5 nm.
11. The passivated contact structure of the solar cell as described in claim 1, characterized in that, The thickness of the first doped layer is 3nm to 100nm.
12. The passivated contact structure of the solar cell as described in claim 1, characterized in that, The first doping element is doped between a plurality of silicon atoms within the first doped layer.
13. The passivated contact structure of the solar cell as described in claim 1, characterized in that, The doping concentration of the first doped element in the first doped layer is 0.5 at% to 25 at%.
14. The passivated contact structure of the solar cell as described in claim 1, characterized in that, The thickness of the second doped layer is 10 nm to 1000 nm.
15. The passivated contact structure of the solar cell as described in claim 1, characterized in that, The thickness of the first doped layer is less than the thickness of the second doped layer.
16. The passivated contact structure of the solar cell as described in claim 3, characterized in that, The first dielectric layer and the second dielectric layer are composed of one or more of the following: oxide layer, nitride layer, oxynitride layer, carbide layer, and amorphous silicon layer.
17. The passivated contact structure of the solar cell as described in claim 3, characterized in that, The first doping element is doped between silicon atoms in the second dielectric layer.
18. A solar cell, characterized in that, The passivated contact structure of the solar cell described in any one of claims 1 to 17 is included.
19. A solar cell module, characterized in that, Including the solar cell described in claim 18 above.
20. A photovoltaic system, characterized in that, Includes the solar cell module described in claim 19 above.