Solar cell and method of manufacturing the same, photovoltaic module

Abstract

The application relates to a solar cell and a preparation method thereof, and a photovoltaic module. The solar cell comprises a semiconductor substrate, the semiconductor substrate has oppositely arranged first and second surfaces; a passivation layer is arranged on the first surface and / or the second surface of the semiconductor substrate, the passivation layer comprises a first passivation layer and a second passivation layer, the first passivation layer is arranged between the semiconductor substrate and the second passivation layer, the signal intensity of hydrogen elements in the first passivation layer increases along a first direction, the signal intensity of hydrogen elements in the second passivation layer decreases along the first direction, the first direction is a direction in which the passivation layer points to the semiconductor substrate; and the content of hydrogen elements in the passivation layer is greater than 20 at%.

Description

Technical Field

[0001] This invention relates to the field of solar photovoltaic module technology, and in particular to a solar cell, its preparation method, and a photovoltaic module. Background Technology

[0002] In the photovoltaic field, the performance optimization of solar cells has always been a research hotspot, among which the passivation layer plays a particularly important role. Passivation layers significantly improve the conversion efficiency and lifespan of solar cells by reducing surface recombination, lowering surface reflection, enhancing cell stability, optimizing cell structure, and reducing series resistance.

[0003] With the continuous development of solar power generation systems, higher demands are being placed on the conversion efficiency and stability of solar cells. To meet these demands, the development of a passivation layer with higher passivation quality and its preparation method is particularly urgent. Summary of the Invention

[0004] To overcome the above-mentioned defects, this application provides a solar cell and its preparation method, as well as a photovoltaic module, which can effectively increase the hydrogen content of the passivation layer in the solar cell, improve the passivation performance of the solar cell, and thus improve the conversion efficiency and service life of the solar cell.

[0005] In a first aspect, embodiments of this application provide a solar cell, the solar cell comprising:

[0006] A semiconductor substrate having a first surface and a second surface disposed opposite to each other;

[0007] A passivation layer is located on a first surface and / or a second surface of the semiconductor substrate. The passivation layer includes a first passivation layer and a second passivation layer. The first passivation layer is located between the semiconductor substrate and the second passivation layer. The signal intensity of hydrogen in the first passivation layer increases along a first direction, and the signal intensity of hydrogen in the second passivation layer decreases along the first direction. The first direction is the direction in which the passivation layer points to the semiconductor substrate.

[0008] The passivation layer contains more than 20 at of hydrogen.

[0009] Secondly, embodiments of this application provide a photovoltaic module, comprising:

[0010] The battery cell layer includes a first surface and a second surface disposed opposite to each other. The battery cell layer includes a plurality of battery strings, each battery string including a plurality of back contact battery cells. An adhesive is disposed between adjacent back contact battery cells.

[0011] The first encapsulation layer is located on the first surface of the battery cell layer;

[0012] The second encapsulation layer located on the second surface of the battery cell layer; and

[0013] A first cover plate located on the surface of the first encapsulation layer and a second cover plate located on the surface of the second encapsulation layer.

[0014] Compared with the prior art, this application has the following significant technical advantages:

[0015] The passivation layer of the solar cell in this application has a stacked structure, which can significantly improve the passivation quality and stability of the solar cell. Specifically, the passivation layer includes a first passivation layer at the bottom and a second passivation layer at the top. Along the first direction, the signal intensity of hydrogen in the first passivation layer increases; that is, within the first passivation layer region, the area closer to the semiconductor substrate is enriched with more hydrogen. This enrichment of hydrogen near the semiconductor substrate is beneficial for repairing defects inside and on the surface of the semiconductor substrate, improving the bulk and surface passivation effects of the solar cell, and reducing carrier recombination. Along the first direction, the signal intensity of hydrogen in the second passivation layer decreases; that is, within the second passivation layer region, the area closer to the first passivation layer has less hydrogen. In this application, hydrogen is abundant in the area far from the first passivation layer, giving the passivation layer surface excellent anti-reflection and mechanical properties. The synergistic effect of the first and second passivation layers in this application is beneficial for improving the overall performance of the solar cell. The hydrogen content in the passivation layer of this application is greater than 20 at. Compared with the traditional passivation layer with a hydrogen content of less than 20%, the passivation layer of this application can significantly reduce the bulk defect state density of solar cells, improve the passivation performance and open-circuit voltage of the cells, thereby improving the conversion efficiency and service life of the cells.

[0016] Other features and advantages of the embodiments of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the embodiments of this application. The objects and other advantages of the embodiments of this application are realized and obtained in accordance with the structures particularly pointed out in the description and the drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a solar cell provided in an embodiment of this application;

[0019] Figure 2 This is a schematic diagram of the structure of a semiconductor substrate provided in an embodiment of this application;

[0020] Figure 3 This is a schematic diagram of another solar cell structure provided in an embodiment of this application;

[0021] Figure 4 This is a schematic diagram of another solar cell structure provided in an embodiment of this application;

[0022] Figure 5 This is a flowchart illustrating the fabrication process of a solar cell, as provided in an embodiment of this application.

[0023] Figure 6 This is a schematic diagram of the structure of a photovoltaic module provided in an embodiment of this application.

[0024] Figure label:

[0025] 1000 - Photovoltaic modules;

[0026] 100-Solar Cell;

[0027] 200 - First cover plate;

[0028] 300 - First encapsulating adhesive layer;

[0029] 400 - Second encapsulating adhesive layer;

[0030] 500 - Second cover plate;

[0031] 1-Semiconductor substrate;

[0032] 11-Third Zone; 111-Third Zone One; 112-Third Zone Two;

[0033] 2-Passivation layer;

[0034] 21-First passivation layer; 211-First region; 212-Second region; 21A-Top surface; 21B-Bottom surface;

[0035] 22 - Second passivation layer;

[0036] 3-Tunneling layer;

[0037] 4-Doped conductive layer;

[0038] 5 - First electrode;

[0039] 6-Second electrode;

[0040] 7-p+ type emitter;

[0041] 8-n+ type back surface field;

[0042] 9-Third electrode;

[0043] 10 - Fourth electrode. Detailed Implementation

[0044] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0045] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0046] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0047] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0048] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of the present invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0049] It should be noted that the steps shown in the flowcharts in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Although a logical order is shown in the flowcharts, the order of the steps in each embodiment is not limited to the order arranged in this specification. In some cases, the implementation steps may be adjusted according to specific needs, and the steps shown or described may be performed in a different order than that shown here.

[0050] In the field of solar cells, passivation layers are typically incorporated to reduce surface recombination and improve conversion efficiency and stability. These passivation layers are usually prepared using plasma-enhanced chemical vapor deposition (PECVD). Compared to PVC processes, PECVD has a lower deposition temperature, allowing passivation materials to be deposited at lower temperatures to form high-quality thin films. However, these films have a lower content of free hydrogen. Specifically, this is mainly because the passivation material is a gas, resulting in a lower ionization rate of free hydrogen. Furthermore, free hydrogen can leak out of the film during deposition, leading to a lower free hydrogen content in the prepared passivation layer. A passivation layer with low free hydrogen content has insufficient passivation capability for surface defects in solar cells, thus limiting the improvement of passivation performance and open-circuit voltage.

[0051] Therefore, embodiments of this application provide a solar cell 100, such as... Figure 1 The diagram shown is a structural schematic of the solar cell of this application. Figure 1 As shown, the solar cell 100 includes:

[0052] Semiconductor substrate 1, semiconductor substrate 1 having a first surface and a second surface disposed opposite to each other;

[0053] Passivation layer 2 is located on the first surface and / or the second surface of semiconductor substrate 1. Passivation layer 2 includes a first passivation layer 21 and a second passivation layer 22. The first passivation layer 21 is located between semiconductor substrate 1 and the second passivation layer 22. The signal intensity of hydrogen element in the first passivation layer 21 increases along a first direction, and the signal intensity of hydrogen element in the second passivation layer 22 decreases along the first direction. The first direction is the direction from the passivation layer to the semiconductor substrate 1.

[0054] The hydrogen content in passivation layer 2 is greater than 20 at.

[0055] In the above scheme, the passivation layer 2 of the solar cell 100 of this application has a stacked structure, which can significantly improve the passivation quality and stability of the solar cell 100. Specifically, the passivation layer 2 includes a first passivation layer 21 at the bottom and a second passivation layer 22 at the top. Along the first direction, the signal intensity of hydrogen in the first passivation layer 21 increases, meaning that the region closer to the semiconductor substrate 1 within the first passivation layer 21 is richer in hydrogen. This hydrogen enrichment near the semiconductor substrate 1 helps repair defects inside and on the surface of the semiconductor substrate 1, improving the bulk and surface passivation effects of the solar cell 100 and reducing carrier recombination. Along the first direction, the signal intensity of hydrogen in the second passivation layer 22 decreases, meaning that the region closer to the first passivation layer 21 within the second passivation layer 22 has less hydrogen. In this application, hydrogen is more abundant in the region far from the first passivation layer 21, giving the passivation layer surface excellent anti-reflection and mechanical properties. The synergistic effect of the first passivation layer 21 and the second passivation layer 22 in this application helps improve the overall performance of the solar cell 100. The hydrogen content in the passivation layer of this application is greater than 20 at%. Compared with the traditional passivation layer with a hydrogen content of less than 20%, the passivation layer 2 of this application can significantly reduce the surface defect state density of the solar cell 100, improve the passivation performance and open circuit voltage of the cell, thereby improving the conversion efficiency and service life of the cell.

[0056] In this application, the hydrogen content in the passivation layer 2 is determined using Fourier-Transform Infrared Spectroscopy (FTIR). Specifically, a double-sided polished high-resistivity silicon wafer or a floating zone silicon wafer (FZ-Si) is used as the substrate for depositing the passivation layer. The passivation layer of this application is deposited on the selected silicon wafer substrate, and the spectrum of the passivation layer is acquired using Fourier-Transform Infrared Spectroscopy. Characteristic absorption peaks related to hydrogen, such as Si-H stretching vibration peaks and NH stretching vibration peaks, are identified in the sample spectrum. By integrating the area of ​​the above characteristic absorption peaks, the hydrogen content in the passivation layer is calculated. It can be understood that the hydrogen content in the passivation layer refers to the atomic content of hydrogen in the passivation layer, expressed in at%, that is, the proportion of hydrogen atoms in the passivation layer.

[0057] In this application, secondary ion mass spectrometry (SIMS) is used to determine the distribution of hydrogen in the passivation layer. When using SIMS to determine the elemental depth distribution, a high-energy particle beam (primary ion, e.g., ...) is employed. , , The sample surface is continuously bombarded by a mass spectrometer to sputter sample atoms (or ions) (i.e., secondary ions). These secondary ions are then separated and detected in real time by a mass spectrometer, thereby obtaining a curve showing the change of signal intensity of a specific element over time (i.e., depth).

[0058] In some embodiments, the semiconductor substrate 1 is an N-type crystalline silicon substrate (or silicon wafer), but it can also be a P-type crystalline silicon substrate (silicon wafer). The crystalline silicon substrate can be, for example, a polycrystalline silicon substrate, a monocrystalline silicon substrate, a microcrystalline silicon substrate, or a silicon carbide substrate. This application does not limit the specific type of the semiconductor substrate 1. When the semiconductor substrate 1 is an N-type substrate, the doping element can be a Group V element such as phosphorus (P), arsenic (As), or tellurium (Te). When the semiconductor substrate 1 is a P-type substrate, the doping element can be a Group III element such as boron (B), aluminum (Al), or gallium (Ga).

[0059] In some embodiments, the first surface of the semiconductor substrate 1 corresponds to the front side of the battery, which is the surface facing the sun (i.e., the light-receiving surface), and the second surface of the semiconductor substrate 1 corresponds to the back side of the battery, which is the surface facing away from the sun (i.e., the back-lighting surface).

[0060] In some embodiments, the first direction is the direction in which the passivation layer 2 points towards the semiconductor substrate 1, and so on. Figure 1 As shown, when the passivation layer 2 is disposed on the first surface of the semiconductor substrate 1, the first direction is... Figure 1 The Z1 direction is shown. When the passivation layer 2 is disposed on the second surface of the semiconductor substrate 1, the first direction is... Figure 1 The Z2 direction is shown.

[0061] In some embodiments, the hydrogen content in the passivation layer 2 is greater than 20 at%. Specifically, the hydrogen content in the passivation layer 2 can be 21 at%, 23 at%, 25 at%, 26 at%, 27 at%, 28 at%, 29 at%, 30 at%, 31 at%, 33 at%, or any value within the range of the above values. Preferably, the hydrogen content in the passivation layer 2 is 26 at% to 30 at%.

[0062] In some embodiments, the hydrogen content in the first passivation layer 21 is 39at% to 45at%. Specifically, the hydrogen content in the first passivation layer 21 can be 39at%, 40at%, 41at%, 42at%, 43at%, 44at%, 45at%, or any value within the range of the above values.

[0063] In some embodiments, the hydrogen content in the second passivation layer 22 is 13at% to 15at%. Specifically, the hydrogen content in the second passivation layer 22 can be 13at%, 13.5at%, 14at%, 14.5at%, 15at%, or any value within the range of the above values.

[0064] This application limits the hydrogen content in the first passivation layer 21 and the hydrogen content in the second passivation layer 22 to the above-mentioned range, so that the hydrogen in the passivation layer 2 is mainly distributed in the first passivation layer 21 close to the semiconductor substrate 1. In this way, the passivation layer 2 can provide excellent passivation effect to the interior and surface of the semiconductor substrate 1, reduce the minority carrier concentration on the surface of the semiconductor substrate 1, reduce the recombination rate of carriers on the surface of the solar cell 100, and improve the open-circuit voltage, fill factor and short-circuit current, thereby improving the conversion efficiency of the solar cell 100.

[0065] In some embodiments, the first passivation layer 21 includes at least one of hydrogenated silicon oxide and hydrogenated silicon nitride. Hydrogenated silicon oxide has a high fixed negative charge density, which can form a very strong field-effect passivation on the surface of the P-type semiconductor substrate 1, significantly reducing the surface recombination rate. Hydrogenated silicon nitride repairs defects, impurities, and dislocations inside the semiconductor substrate 1 by releasing hydrogen atoms, exhibiting excellent bulk passivation capabilities.

[0066] In some embodiments, the second passivation layer 22 comprises at least one of silicon oxynitride and silicon oxide. Silicon oxynitride has a precisely tunable refractive index and, as the second passivation layer 22, exhibits excellent anti-reflection properties, which helps reduce reflection losses in the solar cell 100. Silicon oxynitride also allows more short-wavelength light to penetrate into the cell and be absorbed, which helps improve the short-circuit current. Silicon oxide has lower optical losses and superior passivation effects.

[0067] In some implementations, the first passivation layer 21 can be a single-layer structure or a multi-layer structure, and correspondingly, the second passivation layer 22 can be a single-layer structure or a multi-layer structure.

[0068] The distribution of hydrogen in the first passivation layer 21, the second passivation layer 22, and the semiconductor substrate 1 was determined using secondary ion mass spectrometry (SIMS). The following explanation uses the example of passivation layer 2 being disposed on the second surface of the semiconductor substrate 1. It can be understood that passivation layer 2 disposed on the first surface of the semiconductor substrate 1 also exhibits the same hydrogen distribution pattern.

[0069] In some implementations, continue as Figure 1As shown, the first passivation layer 21 has a top surface 21A and a bottom surface 21B disposed opposite to each other. The bottom surface 21B is disposed between the top surface 21A and the semiconductor substrate 1. The region of the first passivation layer 21 extending from the top surface 21A along a first direction with a thickness of 0~d is denoted as the first region 211. Within the first region 211, the signal intensity of hydrogen increases along the first direction, where d is 0.4D~0.6D, and D is the thickness of the first passivation layer 21. This application controls the distribution of hydrogen in the first passivation layer 21 from the top surface 21A to the center region of the first passivation layer 21. The closer the region of the first region 211 is to the semiconductor substrate 1, the higher the content of hydrogen. Hydrogen exists inside the first passivation layer 21 in the form of Si-H bonds, NH bonds, and OH bonds, which not only gives the first passivation layer 21 an excellent passivation effect, but also allows hydrogen to neutralize the defect charge inside the first passivation layer 21, maintaining the electrical stability of the first passivation layer 21.

[0070] Within the first region 211, the signal intensity of hydrogen increases along the first direction Z1, with a slope of 170~250. Specifically, the slope of the hydrogen signal intensity is 170, 180, 190, 200, 210, 220, 230, 240, 250, or any value within the aforementioned range. Preferably, the slope of the hydrogen signal intensity increases sequentially along the first direction, meaning that within the first region 211, the rate of increase in hydrogen content is greater with increasing depth.

[0071] In some embodiments, a region extending from the bottom surface 21B along a second direction with a thickness of 0 to d is designated as the second region 212, where d is 0.4D to 0.6D and D is the thickness of the first passivation layer 21. Within the second region 212, the signal intensity of hydrogen increases along the second direction. The second direction is parallel to and opposite to the first direction. In this embodiment, the second direction is the Z2 direction. Within the second region 212, the closer to the semiconductor substrate 1, the less hydrogen is distributed, indicating that the hydrogen in the second region 212 has diffused to the surface and interior of the semiconductor substrate 1. This reduces carrier recombination inside and on the surface of the semiconductor substrate 1, improving the passivation effect of the semiconductor substrate 1.

[0072] Within the second region 212, the signal intensity of hydrogen increases along the second direction Z2, and the slope of the hydrogen signal intensity is 0~250. Specifically, the slope of the hydrogen signal intensity is 0, 20, 50, 80, 100, 150, 180, 200, 230, 250, or any value within the above range. Preferably, the slope of the hydrogen signal intensity increases sequentially along the second direction Z2, that is, the slope of the hydrogen signal intensity decreases sequentially along the first direction. The large range of the hydrogen signal intensity slope within the second region 212 indicates that most of the hydrogen in the second region 212 can diffuse into the interior and surface of the semiconductor substrate 1.

[0073] In some embodiments, along the first direction Z1, the slope of the hydrogen signal intensity in the second passivation layer 22 is -180 to -240. Specifically, the slope of the hydrogen signal intensity in the second passivation layer 22 can be -180, -190, -200, -210, -220, -230, -240, or any value within the above range. Along the first direction Z1, the hydrogen intensity decreases at a relatively high rate, indicating a lower hydrogen distribution in the second passivation layer 22. During the fabrication process, a significant amount of hydrogen can diffuse from the second passivation layer 22 into the first passivation layer 21, primarily achieving passivation of the semiconductor substrate 1 and the interface between the semiconductor substrate 1 and the first passivation layer 21. Furthermore, a large amount of hydrogen is enriched on the surface of the second passivation layer 22. Thus, the hydrogen enriched on the surface of the second passivation layer 22 can serve as a hydrogen storage region, providing a guarantee for passivation repair in subsequent processes of the solar cell 100.

[0074] It is understandable that the slope of the hydrogen signal intensity can be positive or negative. When the hydrogen signal intensity increases with depth in a certain film layer, it indicates that the slope of the hydrogen signal intensity in that film layer is positive. Conversely, when the hydrogen signal intensity decreases with depth in a certain film layer, it indicates that the slope of the hydrogen signal intensity in that film layer is negative.

[0075] In some implementations... Figure 2 This is a schematic diagram of the structure of the semiconductor substrate 1 provided in an embodiment of this application, as shown below. Figure 2 As shown, in the region (third region 11) extending 0~1μm from the second surface of the semiconductor substrate 1 along the first direction Z1, the relative intensity of hydrogen decreases along the first direction Z1. It can be understood that the hydrogen in the semiconductor substrate 1 originates from the passivation layer 2. The hydrogen in the passivation layer 2 first diffuses to the second surface of the semiconductor substrate 1 and then diffuses into the interior of the semiconductor substrate 1. During the diffusion process, the closer to the second surface of the semiconductor substrate 1, the higher the hydrogen content, and the greater the probability of it being captured. The captured hydrogen can combine with defects, impurities, and other atoms in the semiconductor substrate 1, thus exerting a passivation effect.

[0076] In some implementations, continue as Figure 2 As shown, in a region (third region - 111) extending from the second surface of the semiconductor substrate 1 along the first direction Z1 with a thickness of 0~0.5μm, the relative intensity of hydrogen decreases along the first direction, and the slope of the relative intensity of hydrogen is -120~-50. Specifically, the slope of the relative intensity of hydrogen can be -120, -110, -100, -90, -80, -70, -60, -50 or any value within the range of any two of the above values.

[0077] In some embodiments, within a region (third region 112) extending 0.5 μm to 1 μm in thickness from the first surface of the semiconductor substrate 1 along the first direction Z1, the relative intensity of hydrogen decreases along the first direction Z1, and the slope of the relative intensity of hydrogen is -50 to -5. Specifically, the slope of the relative intensity of hydrogen can be -50, -45, -40, -35, -30, -20, -20, -5, or any value within the range of any two of the above values.

[0078] Due to the properties of the semiconductor substrate 1 material itself, there are far more dangling bonds on the surface of the semiconductor substrate 1 than inside the semiconductor substrate 1. Moreover, during the fabrication and processing of the semiconductor substrate 1, processes such as cutting, masking, and polishing leave damage on the surface of the semiconductor substrate 1, and this damage becomes smaller with increasing depth, causing defects such as lattice distortion, dislocations, and microcracks in this area. In this application, compared to the second third region 112, the first third region 111 is closer to the surface of the semiconductor substrate 1. The slope value of the relative intensity of hydrogen in the first third region 111 is greater than that in the second third region 112. That is, as the depth increases, the rate of decrease of hydrogen in the third region 111 is greater than that in the second third region 112. This indicates that the third region 111 contains more hydrogen. More hydrogen can combine with impurities and defects in the third region 111, effectively passivating the dangling bonds in the third region 111 of the semiconductor substrate 1, reducing the recombination rate. Moreover, it can also effectively suppress lattice damage generated in the semiconductor substrate 1 during processes such as cutting and masking, reduce the adsorption and enrichment of metal impurities and organic matter in the third region 111 of the semiconductor substrate 1, thereby improving the passivation performance of the semiconductor substrate 1, reducing carrier recombination, and improving battery efficiency.

[0079] In some embodiments, the refractive index of the first passivation layer 21 is greater than that of the second passivation layer 22. By using a superposition structure of the first passivation layer 21 with a higher refractive index and the second passivation layer 22 with a lower refractive index, the reflectivity of the passivation layer 2 can be effectively reduced.

[0080] In some embodiments, the refractive index of the first passivation layer 21 is 1.8 to 2.3. Specifically, the refractive index of the first passivation layer 21 can be 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, or any value within the above range. Controlling the refractive index of the first passivation layer 21 within the above range provides a high negative fixed charge density, enabling good field-effect passivation for both p-type and n-type semiconductor substrates.

[0081] In some embodiments, the refractive index of the second passivation layer 22 is 1.0 to 1.7. Specifically, the refractive index of the first passivation layer 21 can be 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or any value within the above range.

[0082] The refractive index of the semiconductor substrate 1 is generally between 3.0 and 5.0. This application enables the semiconductor substrate 1, the first passivation layer 21 and the second passivation layer 22 to form a structure with a gradient refractive index, which can effectively reduce the reflection loss on the surface of the solar cell 100 and increase the light-harvesting ability of the solar cell 100, extend the propagation path of light in the solar cell 100 and increase light absorption.

[0083] In some embodiments, the thickness difference between the first passivation layer 21 and the second passivation layer 22 is less than 100 nm. Specifically, the thickness difference between the first passivation layer 21 and the second passivation layer 22 can be 1 nm, 10 nm, 20 nm, 35 nm, 50 nm, 70 nm, 80 nm, 93 nm, 99 nm, or any value within the above range. By controlling the thickness difference between the first passivation layer 21 and the second passivation layer 22 within the above range, while ensuring that the passivation layer 2 has excellent passivation performance, adjusting the thickness of the first passivation layer 21 and the second passivation layer 22 results in a lower reflectivity and higher transmittance of the passivation layer within the target spectral range (typically 300 nm to 120 nm), thereby improving the optical gain of the passivation layer 2, reducing electrical losses, and contributing to improving the overall performance of the solar cell 100.

[0084] In some embodiments, the thickness of the first passivation layer 21 is 20 nm to 150 nm. Specifically, the thickness of the first passivation layer 21 can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, or any value within the above range. Controlling the thickness of the first passivation layer 21 within the above range is beneficial for obtaining excellent passivation performance.

[0085] In some embodiments, the thickness of the second passivation layer 22 is 20 nm to 150 nm. Specifically, the thickness of the second passivation layer 22 can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, or any value within the above range. Controlling the thickness of the second passivation layer 22 within the above range is beneficial for obtaining excellent anti-reflection performance and reducing optical losses.

[0086] In some implementations... Figure 3This is a schematic diagram of another solar cell 100 provided in an embodiment of this application, as shown below. Figure 3 As shown, a tunneling layer 3 and a doped conductive layer 4 are further disposed between the semiconductor substrate 1 and the passivation layer 2 located on the second surface of the semiconductor substrate 1. That is, the solar cell 100 of this application is a tunnel oxide passivated contact (TOPCon) cell. In the TOPCon cell, the passivation layer 2 containing hydrogen can passivate the lattice defects inside the doped conductive layer 4, reduce its resistivity, and improve carrier transport. The hydrogen in the passivation layer 2 can also diffuse to the interface between the tunneling layer 3 and the semiconductor substrate 1, dangling bonds at the saturated interface, and the hydrogen can also diffuse into the interior of the semiconductor substrate 1, passivating impurities and defects in the semiconductor substrate 1 and improving the passivation performance of the solar cell 100.

[0087] In some embodiments, the solar cell 100 further includes an antireflection layer (not shown in the figures) located on the first surface of the semiconductor substrate 1, the antireflection layer being located on the surface of the passivation layer on the first surface of the semiconductor substrate 1.

[0088] In some implementations, continue as Figure 3 As shown, the solar cell 100 also includes a first electrode 5 located on the first surface of the semiconductor substrate 1 and a second electrode 6 located on the second surface of the semiconductor substrate 1. The first electrode 5 is located on the passivation layer 2 on the first surface of the semiconductor substrate 1, and the second electrode 6 is located on the passivation layer 2 on the second surface of the semiconductor substrate 1.

[0089] In some implementations... Figure 4 This is a schematic diagram of the structure of another solar cell 100 provided in the embodiments of this application, as shown below. Figure 4 As shown, the solar cell 100 also includes a p+ type emitter 7 and an n+ type back surface field 8 located between the semiconductor substrate 1 and the passivation layer 2 located on the second surface of the semiconductor substrate 1. Therefore, the solar cell 100 of this application is a back contact (BC) cell. In the BC cell, the passivation layer 2 located on the first surface of the semiconductor substrate 1 can passivate the front side of the semiconductor substrate 1, saturating dangling bonds and exhibiting excellent passivation performance. Simultaneously, since there are no electrodes on the front side of the BC cell, the hydrogen-containing passivation layer 2 of this application can provide excellent anti-reflection effects, effectively reducing optical losses. The passivation layer 2 located on the second surface of the semiconductor substrate 1 can effectively repair lattice losses and defects generated in the p+ type emitter 7 and n+ type back surface field 8 regions, greatly reducing the recombination rate in these regions and improving the conversion efficiency of the solar cell 100.

[0090] In some implementations, continue as Figure 4As shown, the solar cell 100 also includes a third electrode 9 and a fourth electrode 10 located on the second surface of the semiconductor substrate 1, wherein the third electrode 9 and the fourth electrode 10 are both disposed on the surface of the passivation layer 2, the third electrode 9 corresponds to the p+ type emitter 7, and the fourth electrode 10 corresponds to the n+ type back surface field 8.

[0091] This application also provides a method for preparing a solar cell 100, used to prepare the aforementioned solar cell 100. Figure 5 A flowchart illustrating the fabrication process of the solar cell 100 provided in this application embodiment is shown below. Figure 5 As shown, the fabrication method of solar cell 100 includes the following steps:

[0092] A semiconductor substrate 1 is provided, the semiconductor substrate 1 having a first surface and a second surface disposed opposite to each other;

[0093] The first gas is deposited on the first surface and / or the second surface using plasma-enhanced chemical vapor deposition to obtain a first passivation layer 21.

[0094] The second gas is deposited on the first and / or second surfaces using plasma-enhanced chemical vapor deposition to obtain a second passivation layer 22.

[0095] The first gas and / or the second gas includes a gaseous silicon source and hydrogen, and the first gas and / or the second gas also includes at least one of a gaseous oxygen source and a gaseous nitrogen source, and the temperature of the first deposition and / or the second deposition is 350°C to 440°C.

[0096] In the above scheme, this application uses plasma-enhanced chemical vapor deposition to prepare the first passivation layer 21 and the second passivation layer 22. During the deposition process, by introducing hydrogen gas and controlling the deposition temperature, the hydrogen gas can absorb relatively low energy to dissociate into free hydrogen, while reducing the escape of free hydrogen, thereby depositing more free hydrogen in the passivation layer. Moreover, this application sequentially uses plasma-enhanced chemical vapor deposition to prepare the first passivation layer 21 and the second passivation layer 22 to obtain a stacked passivation layer structure, which can not only improve the bulk passivation and surface passivation effect of the solar cell 100 and reduce carrier recombination, but also enable the solar cell 100 to have excellent anti-reflection performance and mechanical properties. As a result, the hydrogen content in the passivation layer prepared in this application is greater than 20 at%, compared with the traditional passivation layer with a hydrogen content of less than 20%. The passivation layer of this application can significantly reduce the bulk surface defect state density of the solar cell 100, improve the passivation performance and open circuit voltage of the cell, thereby improving the conversion efficiency and service life of the cell.

[0097] The fabrication process of the solar cell 100 of this application is described in detail below.

[0098] S100, a semiconductor substrate 1 is provided, the semiconductor substrate 1 having a first surface and a second surface disposed opposite to each other.

[0099] In some embodiments, the first surface of the semiconductor substrate 1 corresponds to the front side of the battery, which is the surface facing the sun (i.e., the light-receiving surface), and the second surface of the semiconductor substrate 1 corresponds to the back side of the battery, which is the surface facing away from the sun (i.e., the back-lighting surface).

[0100] In some embodiments, the semiconductor substrate 1 is an N-type crystalline silicon substrate (or silicon wafer), but it can also be a P-type crystalline silicon substrate (silicon wafer). The crystalline silicon substrate (silicon substrate) can be, for example, a polycrystalline silicon substrate, a monocrystalline silicon substrate, a microcrystalline silicon substrate, or a silicon carbide substrate. This application does not limit the specific type of the semiconductor substrate 1. When the semiconductor substrate 1 is an N-type substrate, the doping element can be a Group V element such as phosphorus (P), arsenic (As), or tellurium (Te). When the semiconductor substrate 1 is a P-type substrate, the doping element can be a Group III element such as boron (B), aluminum (Al), or gallium (Ga).

[0101] In some embodiments, the thickness of the semiconductor substrate 1 is 60 μm to 240 μm, specifically 60 μm, 80 μm, 90 μm, 100 μm, 120 μm, 150 μm, 200 μm or 240 μm or any value within the range of any two of the above values.

[0102] S200, the first gas is deposited on the first surface and / or the second surface using plasma-enhanced chemical vapor deposition to obtain a first passivation layer 21.

[0103] In some embodiments, the temperature of the first deposition is 350°C to 440°C. Specifically, the temperature of the first deposition can be 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, or any value within the range of any two of the above values. This application controls the temperature of the first deposition to be 350°C to 440°C and introduces hydrogen gas during the first deposition process. This can improve the ionization rate of free hydrogen and reduce the escape of free hydrogen, allowing more free hydrogen dissociated from the first deposition to be distributed in the first passivation layer 21, thereby increasing the hydrogen content of the first passivation layer 21. If the temperature of the first deposition exceeds 440°C, the energy required for the first deposition is too high. During the first deposition process, the dissociated free hydrogen has sufficient energy to overcome the binding force, causing free hydrogen to overflow from the first passivation layer 21. At the same time, hydrogen bound in the form of Si-H or NH bonds has limited thermal stability and will break at high temperatures, resulting in a significant reduction in the hydrogen content in the first passivation layer 21. If the temperature of the first deposition is less than 350°C, the energy provided is insufficient, and the first gas decomposes incompletely, forming "dead hydrogen" or "inactive hydrogen," which greatly reduces the hydrogen content in the first passivation layer 21, thereby reducing the passivation effect of the first passivation layer 21. Moreover, the surface mobility of the first gas reaching the semiconductor substrate 1 is greatly reduced, resulting in a large number of loose and porous structures in the film formed during the first deposition process, leading to more defects inside the first passivation layer 21 and further deteriorating the passivation performance.

[0104] In some embodiments, the first gas includes a gaseous silicon source and hydrogen, and optionally a gaseous oxygen source and a gaseous nitrogen source. It is understood that when the first gas includes a gaseous silicon source, a gaseous nitrogen source, and hydrogen, the material of the passivation layer is hydrogenated silicon nitride. When the first gas includes a gaseous silicon source, a gaseous nitrogen source, a gaseous oxygen source, and hydrogen, the material of the passivation layer is hydrogenated silicon oxynitride or hydrogenated silicon oxide. Preferably, the formed first passivation layer 21 includes at least one of hydrogenated silicon oxide and hydrogenated silicon nitride.

[0105] In some embodiments, the gaseous silicon source includes silane, and the flow rate of the gaseous silicon source is 1000 sccm to 5000 sccm, for example, it can be 1000 sccm, 1500 sccm, 2000 sccm, 2500 sccm, 3000 sccm, 4000 sccm, 4500 sccm, 5000 sccm or any value within the range of any two of the above values.

[0106] In some embodiments, the gaseous nitrogen source includes ammonia, and the flow rate of the gaseous nitrogen source is 50 sccm to 600 sccm, for example, it can be 50 sccm, 100 sccm, 150 sccm, 200 sccm, 250 sccm, 300 sccm, 400 sccm, 500 sccm, 600 sccm or any value within the range of any two of the above values.

[0107] In some embodiments, the flow rate ratio of gaseous silicon source to gaseous nitrogen source is (5~15):1. This application controls the flow rate of gaseous silicon source and gaseous nitrogen source, and further combines this with the temperature control of the first deposition, thereby regulating the refractive index of the first passivation layer 21 to 1.8~2.3.

[0108] In some embodiments, the gaseous oxygen source includes nitrous oxide (nitrous oxide). The flow rate of the gaseous oxygen source is 500 sccm to 5000 sccm, for example, it can be 500 sccm, 800 sccm, 1000 sccm, 1500 sccm, 2000 sccm, 2500 sccm, 3000 sccm, 3500 sccm, 4000 sccm, 5000 sccm or any value within the range of any two of the above values.

[0109] In some embodiments, the ratio of the flow rates of the gaseous nitrogen source to the gaseous oxygen source is >5:1. This application controls the flow rates of the gaseous nitrogen source and the gaseous oxygen source to further control the temperature of the first deposition, thereby adjusting the refractive index of the first passivation layer 21 to 1.8~2.3.

[0110] In some embodiments, the hydrogen flow rate is 200 sccm to 30000 sccm. Specifically, the hydrogen flow rate is 200 sccm, 500 sccm, 1000 sccm, 3000 sccm, 5000 sccm, 8000 sccm, 10000 sccm, 15000 sccm, 20000 sccm, 23000 sccm, 27000 sccm, 30000 sccm, or any value within the range of any two of the above values. Controlling the hydrogen flow rate within the above range can provide a certain hydrogen source for the first deposition process, increasing the hydrogen content in the first passivation layer 21. If the hydrogen flow rate is too low, the hydrogen content in the first passivation layer 21 cannot be effectively increased. If the hydrogen flow rate is too high, it will dilute the first gas, resulting in a loose first passivation layer 21 and severely deteriorating the passivation quality.

[0111] In some embodiments, during the first deposition process, an auxiliary gas is introduced, including at least one of nitrogen and argon. By adding the auxiliary gas, it serves as a carrier gas for the first deposition material and also stabilizes the plasma during the first deposition process.

[0112] It should be noted that a first deposition can be performed sequentially on the first surface and the second surface of the semiconductor substrate 1 to prepare a first passivation layer 21 located on the first surface of the semiconductor substrate 1 and a first passivation layer 21 located on the second surface of the semiconductor substrate 1.

[0113] S300. The second gas is deposited on the first surface and / or the second surface of the semiconductor substrate 1 using plasma-enhanced chemical vapor deposition to obtain the second passivation layer 22.

[0114] In some embodiments, the temperature of the second deposition is 350°C to 440°C. Specifically, the temperature of the second deposition can be 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, or any value within the range of any two of the above values. This application controls the temperature of the second deposition to be 350°C to 440°C and introduces hydrogen gas during the second deposition process. This can improve the ionization rate of free hydrogen, reduce the escape of free hydrogen from the formed second passivation layer 22, and reduce the escape of hydrogen from the first passivation layer 21, thereby increasing the hydrogen content in the first passivation layer 21 and the second passivation layer 22, such that the hydrogen content in the first passivation layer 21 is 39 at% to 45 at%, and the hydrogen content in the second passivation layer 22 is 13 at% to 15 at%.

[0115] If the temperature of the second deposition exceeds 440℃, the energy required for the second deposition is too high. During the second deposition process, the dissociated free hydrogen has sufficient energy to overcome the binding force and diffuse out from the first passivation layer 21 and the second passivation layer 22. At the same time, the hydrogen bound in the form of Si-H or NH bonds has limited thermal stability and will break at high temperatures, resulting in a significant reduction in the hydrogen content in the second passivation layer 22. If the temperature of the second deposition is less than 350℃, the energy provided is insufficient, and the second gas decomposes incompletely, forming "dead hydrogen" or "inactive hydrogen," which greatly reduces the hydrogen content in the second passivation layer 22, thereby reducing the passivation effect of the second passivation layer 22. Moreover, the surface mobility of the second gas reaching the semiconductor substrate 1 is greatly reduced, resulting in a large number of loose and porous structures in the film formed during the second deposition process, leading to more defects inside the second passivation layer 22 and further deteriorating the passivation performance.

[0116] Preferably, the temperature difference between the first deposition and the second deposition is less than 30°C. Specifically, the temperature difference between the first deposition and the second deposition can be 0°C, 5°C, 10°C, 15°C, 30°C, 25°C, 30°C, or any value within the range of any two of the above values. Controlling the temperature difference between the first deposition and the second deposition to be less than 30°C in this application is beneficial for obtaining a second passivation layer 22 with a high free hydrogen content, while simultaneously preventing the escape of free hydrogen from the first passivation layer 21 due to the deposition temperature of the second deposition process. Preferably, the temperature of the first deposition is lower than the temperature of the second deposition. A higher temperature second deposition process can obtain a dense and high-quality film layer, which is beneficial for improving the optical performance and mechanical protection of the solar cell 100.

[0117] In some embodiments, the second gas includes a gaseous silicon source and hydrogen, and optionally a gaseous oxygen source and a gaseous nitrogen source. It is understood that when the second gas includes a gaseous silicon source, a gaseous nitrogen source, and hydrogen, the material of the passivation layer is hydrogenated silicon nitride. When the second gas includes a gaseous silicon source, a gaseous nitrogen source, a gaseous oxygen source, and hydrogen, the material of the passivation layer is hydrogenated silicon oxynitride or hydrogenated silicon oxide. Preferably, the formed second passivation layer 22 includes at least one of hydrogenated silicon oxynitride and hydrogenated silicon oxide.

[0118] In some embodiments, the gaseous silicon source includes silane, and the flow rate of the gaseous silicon source is 1000 sccm to 5000 sccm, for example, it can be 1000 sccm, 1500 sccm, 2000 sccm, 2500 sccm, 3000 sccm, 4000 sccm, 4500 sccm, 5000 sccm or any value within the range of any two of the above values.

[0119] In some embodiments, the gaseous nitrogen source includes ammonia, and the flow rate of the gaseous nitrogen source is 50 sccm to 600 sccm, for example, it can be 50 sccm, 100 sccm, 150 sccm, 200 sccm, 250 sccm, 300 sccm, 400 sccm, 500 sccm, 600 sccm or any value within the range of any two of the above values.

[0120] In some embodiments, the flow rate ratio of gaseous silicon source to gaseous nitrogen source is (5~15):1. This application controls the flow rate of gaseous silicon source and gaseous nitrogen source to further control the temperature of the first deposition, thereby adjusting the refractive index of the second passivation layer 22 to 1.0~1.7.

[0121] In some embodiments, the gaseous oxygen source includes nitrous oxide (nitrous oxide). The flow rate of the gaseous oxygen source is 500 sccm to 5000 sccm, for example, it can be 500 sccm, 800 sccm, 1000 sccm, 1500 sccm, 2000 sccm, 2500 sccm, 3000 sccm, 3500 sccm, 4000 sccm, 5000 sccm or any value within the range of any two of the above values.

[0122] In some embodiments, the ratio of the flow rates of the gaseous nitrogen source to the gaseous oxygen source is >5:1. This application controls the flow rates of the gaseous nitrogen source and the gaseous oxygen source to further control the temperature of the first deposition, thereby adjusting the refractive index of the second passivation layer 22 to 1.0~1.7.

[0123] In some embodiments, the hydrogen flow rate is 200 sccm to 30000 sccm. Specifically, the hydrogen flow rate is 200 sccm, 500 sccm, 1000 sccm, 3000 sccm, 5000 sccm, 8000 sccm, 10000 sccm, 15000 sccm, 20000 sccm, 23000 sccm, 27000 sccm, 30000 sccm, or any value within the range of any two of the above values. Controlling the hydrogen flow rate within the above range can provide a certain hydrogen source for the second deposition process, increasing the hydrogen content in the second passivation layer 22. If the hydrogen flow rate is too low, the hydrogen content in the second passivation layer 22 cannot be effectively increased. If the hydrogen flow rate is too high, it will dilute the second gas, resulting in a loose second passivation layer 22 and severely deteriorating the passivation quality.

[0124] In some embodiments, an auxiliary gas is introduced during the second deposition process. The auxiliary gas includes at least one of nitrogen and argon. By adding the above-mentioned auxiliary gas, it serves as a carrier gas for the second deposition material and can also stabilize the plasma during the second deposition process.

[0125] It should be noted that a second deposition can be performed sequentially on the first surface and the second surface of the semiconductor substrate 1 to prepare a second passivation layer 22 located on the first surface of the semiconductor substrate 1 and a second passivation layer 22 located on the second surface of the semiconductor substrate 1.

[0126] In some embodiments, when the prepared solar cell 100 is a TOPCon cell, before S200, a tunneling layer 3 and a doped conductive layer 4 are formed on the second surface of the semiconductor substrate 1. It can be understood that the first passivation layer 21 formed in S300 on the second surface of the semiconductor substrate is located on the surface of the doped conductive layer 4.

[0127] In some embodiments, a tunneling layer 3 is formed on the second surface of the semiconductor substrate 1, and a doped conductive layer 4 is formed on the surface of the tunneling layer 3. The tunneling layer 3 can be a single-layer or multi-layer structure made of one or more dielectric materials with tunneling properties, such as silicon oxide, silicon nitride, silicon oxynitride, molybdenum oxide, hafnium oxide, silicon carbide, magnesium fluoride, nanocrystalline silicon, intrinsic amorphous silicon, and intrinsic polycrystalline silicon. The tunneling layer 3 can be formed using thermal oxidation, chemical vapor deposition, physical vapor deposition, or atomic layer deposition. An initial silicon layer is formed on the surface of the tunneling layer 3 using chemical vapor deposition, physical vapor deposition, or atomic layer deposition. Then, a diffusion process is used to highly concentrate the initial silicon layer with a gas containing a dopant source to form the doped conductive layer 4. The diffusion process causes the dopant source to react with the surface of the initial silicon layer, forming doped atoms that diffuse into the interior of the initial silicon layer. Alternatively, the dopant source gas can be mixed during silicon layer deposition to directly deposit the doped conductive layer containing the dopant source. It is understood that the conductivity type of the dopant source is the same as that of the dopant element in semiconductor substrate 1. For example, an intrinsic amorphous silicon layer is deposited using silane via LPCVD (low-pressure chemical vapor deposition), followed by high-temperature treatment to crystallize the intrinsic amorphous silicon layer, thus transforming it into a polycrystalline silicon layer. During the high-temperature treatment, a phosphorus source gas (e.g., phosphorus source gas) is simultaneously introduced. Phosphorus doping was achieved by high-temperature treatment at 800℃~1000℃ to obtain a doped conductive layer 4.

[0128] It is understandable that while forming the doped conductive layer 4, a layer of silicon phosphate glass (PSG) will be formed on the surface of the doped conductive layer 4 and the first surface of the semiconductor substrate 1. The quality of this silicon phosphate glass is very poor and needs to be removed later, for example, by rinsing and etching with hydrofluoric acid solution.

[0129] In some embodiments, after S300, a first electrode 5 is formed on a first surface of the semiconductor substrate 1, and a second electrode 6 is formed on a second surface of the semiconductor substrate 1. The first electrode 5 and the second electrode 6 can be prepared by screen printing combined with sintering, or at least one of metal vapor deposition and electroplating can be used to form the first electrode 5 and the second electrode 6.

[0130] It should be noted that the specific materials of the first electrode 5 and the second electrode 6 are not limited in the embodiments of this application. For example, the first electrode 5 and / or the second electrode 6 may include one or more of aluminum, silver, gold, nickel, molybdenum, or copper.

[0131] In some embodiments, when the prepared solar cell 100 is a BC cell, before S200, it further includes forming an alternately arranged p+ type emitter 7 and n+ type back surface field 8 on the second surface of the semiconductor substrate 1. It can be understood that the first passivation layer 21 formed in S300 on the second surface of the semiconductor substrate 1 is located on the surface of the p+ type emitter 7 and the n+ type back surface field 8.

[0132] In some embodiments, a mask layer may first be deposited on the second surface of the semiconductor substrate 1, the material of which is, for example, [material name missing]. or Then, using laser grooving technology, the mask layer is selectively ablated according to the pre-designed image. Through two laser scans, the openings of the p+ type emitter 7 and the n+ type back surface field 8 are obtained. The images of the two laser scans are arranged in an interdigitated pattern. Then, a P-type conductive liquid source (such as a boron latex source) is coated in the opening of the corresponding p+ type emitter 7, and an N-type conductive liquid source (such as a phosphorus latex source) is coated in the opening of the n+ type back surface field 8. Low-temperature thermal driving is performed through a chain diffusion furnace to pre-deposit dopant atoms onto the semiconductor substrate surface at the laser opening to form a shallow junction. Finally, laser doping is performed to obtain the p+ type emitter 7 and the n+ type back surface field 8.

[0133] In some embodiments, after S300, a third electrode 9 and a fourth electrode 10 are formed on the second surface of the semiconductor substrate 1, wherein the third electrode 9 corresponds to the p+ type emitter 7 and the fourth electrode 10 corresponds to the n+ type back surface field 8. The third electrode 9 and the fourth electrode 10 can be prepared by screen printing combined with sintering, or by at least one of metal evaporation and electroplating.

[0134] It should be noted that the specific materials of the third electrode 9 and the fourth electrode 10 are not limited in the embodiments of this application. For example, the third electrode 9 and / or the fourth electrode 10 include one or more of aluminum, silver, gold, nickel, molybdenum or copper.

[0135] It should be noted that the fabrication of the first electrode 5, the second electrode 6, the third electrode 9, and the fourth electrode 10 involves annealing or metallization sintering. The high temperatures involved in these processes break the Si-H and NH bonds in the passivation layer 2, releasing hydrogen atoms. These released hydrogen atoms diffuse into the interior of the semiconductor substrate 1 and combine with the dangling bonds of the semiconductor substrate 1 to form stable Si-H bonds, thereby eliminating recombination centers and achieving excellent passivation effects. Consequently, in the semiconductor substrate 1, along the first direction, the relative intensity of hydrogen elements decreases in the region extending 0-1 μm along the first direction. Furthermore, in the region extending 0-0.5 μm along the first direction, the slope of the relative intensity of hydrogen elements is -120 to -50, and in the region extending 0.5 μm-1 μm along the first direction, the slope of the relative intensity of hydrogen elements is -50 to -5.

[0136] It should be noted that, unless otherwise stated, the various operational steps in this application may or may not be performed in a specific order. The embodiments of this application do not limit the order of steps in preparing solar cells and can be adjusted according to the actual production process.

[0137] The performance of the solar cells prepared in this application will be verified below:

[0138] An experimental group and a control group were set up. The experimental group consisted of solar cells prepared using the method described in this application. The difference between the control group and the experimental group was that the deposition temperature in the first and second deposition processes of the control group was greater than 440℃, and no hydrogen gas was introduced. Infrared spectroscopy was performed on the passivation layers prepared in both the experimental and control groups. In the obtained spectra, the absorption peak position of the Si-H stretching vibration peak was 2072~2272 cm⁻¹. -1 By integrating the infrared spectra of the experimental and control groups, the integrated area of ​​the experimental group was found to be 2.74–2.91, indicating a hydrogen content of 26 at%–30 at% in the passivation layer. The integrated area of ​​the control group was 1.88–2.09, indicating a hydrogen content of 17 at%–20 at% in the passivation layer. The calculated hydrogen content in the passivation layer of the experimental group was 50%–60% higher than that of the control group, demonstrating that the preparation method of this application can obtain a passivation layer with high hydrogen content.

[0139] The semiconductor substrates, first passivation layer, and second passivation layer of the experimental group and control group were subjected to secondary ion mass spectrometry measurements, and the spectral results are as follows:

[0140] In the first passivation layer of the experimental group, the signal intensity of hydrogen was between 4000 and 22000. With increasing depth, the signal intensity of hydrogen showed an increasing trend, rising from 4000-7000 to 18000-22000. In the first passivation layer of the control group, the signal intensity of hydrogen was 2000-19000. Calculations showed that the hydrogen content in the first passivation layer of the control group was 70%-80% of that in the experimental group.

[0141] In the second passivation layer of the experimental group, the signal intensity of hydrogen was between 4000 and 15000. With increasing depth, the signal intensity decreased from 10000-150000 to 4000-7000. In the second passivation layer of the control group, the signal intensity of hydrogen was between 2000 and 4000. Calculations showed that the hydrogen content in the second passivation layer of the control group was 10%-20% of that in the experimental group.

[0142] In the experimental group's semiconductor substrate, within a region (third region) extending 0-1 μm from the first and / or second surfaces along the first direction, the hydrogen signal intensity ranged from 800 to 22000, decreasing with depth from 18000-22000 to 800-000. In the control group's semiconductor substrate, within the same region (third region) extending 0-1 μm from the first and / or second surfaces along the first direction, the hydrogen signal intensity ranged from 500 to 19000. Calculations showed that the hydrogen content in the third region of the control group's semiconductor substrate was 90%-95% of that in the experimental group's semiconductor substrate.

[0143] The photoluminescence intensity (PL intensity, i.e., PL brightness) of the passivation layers in the experimental and control groups was measured using a PL Imaging (PLI) system. The PL brightness of the passivation layer in the experimental group was about 8000 a.u. higher than that in the control group. Calculations showed that the open-circuit voltage of the solar cell in the experimental group was more than 1.6 mV higher and the conversion efficiency was more than 0.19% higher. This indicates that the passivation layer of the solar cell in this application has a high hydrogen content, which can significantly reduce the surface defect state density of the solar cell, improve the passivation performance and open-circuit voltage, and thus improve the conversion efficiency of the cell.

[0144] Thirdly, embodiments of this application provide a photovoltaic module 1000, including a battery string formed by electrical connections of the aforementioned solar cells.

[0145] Figure 6 For a schematic diagram of the photovoltaic module provided in the embodiments of this application, please refer to [link / reference]. Figure 6 The photovoltaic module 1000 includes a first cover plate 200, a first encapsulating layer 300, a solar cell string, a second encapsulating layer 400, and a second cover plate 500.

[0146] In some embodiments, the solar cell string includes a plurality of solar cells 100 as described above connected by conductive strips. The connection between the solar cells 100 can be partially stacked or spliced.

[0147] In some embodiments, the first cover plate 200 and the second cover plate 500 can be transparent or opaque covers, such as glass covers or plastic covers.

[0148] The first encapsulating adhesive layer 300 is in contact with and bonded to the first cover plate 200 and the battery string on both sides, respectively. The second encapsulating adhesive layer 400 is in contact with and bonded to the second cover plate 500 and the battery string on both sides, respectively. The first encapsulating adhesive layer 300 and the second encapsulating adhesive layer 400 can be ethylene-vinyl acetate copolymer (EVA) film, polyethylene octene coelastomer (POE) film, or polyethylene terephthalate (PET) film, respectively.

[0149] The photovoltaic module 1000 can also be fully encapsulated on the sides, that is, the sides of the photovoltaic module 1000 are completely covered and encapsulated with encapsulating tape to prevent lamination shift during the lamination process.

[0150] The photovoltaic module 1000 also includes an edge sealing component, which is fixedly encapsulated on a portion of the edge of the photovoltaic module 1000. This edge sealing component can be fixedly encapsulated on the edge of the photovoltaic module 1000 near a corner. The edge sealing component can be a high-temperature resistant tape. This high-temperature resistant tape has excellent high-temperature resistance properties and will not decompose or detach during lamination, ensuring reliable encapsulation of the photovoltaic module 1000. The two ends of the high-temperature resistant tape are respectively fixed to the second cover plate 500 and the first cover plate 200. The two ends of the high-temperature resistant tape can be bonded to the second cover plate 500 and the first cover plate 200 respectively, while the middle portion can limit the side of the photovoltaic module 1000, preventing lamination displacement of the photovoltaic module 1000 during the lamination process.

[0151] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A solar cell, characterized in that, The solar cell includes: A semiconductor substrate having a first surface and a second surface disposed opposite to each other; A passivation layer is located on a first surface and / or a second surface of the semiconductor substrate. The passivation layer includes a first passivation layer and a second passivation layer. The first passivation layer is located between the semiconductor substrate and the second passivation layer. The signal intensity of hydrogen in the first passivation layer increases along a first direction, and the signal intensity of hydrogen in the second passivation layer decreases along the first direction. The first direction is the direction in which the passivation layer points to the semiconductor substrate. The passivation layer contains more than 20 at of hydrogen.

2. The solar cell according to claim 1, characterized in that, The hydrogen content in the first passivation layer is 39 at% to 45 at%; and / or the hydrogen content in the second passivation layer is 13 at% to 15 at%.

3. The solar cell according to claim 1, characterized in that, The first passivation layer comprises at least one of hydrogenated silicon oxide and hydrogenated silicon nitride; and / or The second passivation layer comprises at least one of hydrogenated silicon oxynitride and hydrogenated silicon oxide; and / or The first passivation layer is a single-layer or multi-layer structure; and / or The second passivation layer is a single-layer or multi-layer structure.

4. The solar cell according to claim 1, characterized in that, The first passivation layer has a top surface and a bottom surface disposed opposite to each other, the bottom surface being located between the top surface and the semiconductor substrate; The thickness of the first passivation layer is denoted as D. Within a region of thickness 0 to d extending along the first direction from the top surface, the signal intensity of the hydrogen element increases along the first direction, with a slope of 170 to 250, and d being 0.4D to 0.6D; and / or The thickness of the first passivation layer is denoted as D. In the region with a thickness of 0 to d extending along the second direction from the bottom surface, the signal intensity of the hydrogen element increases along the second direction. The slope of the signal intensity of the hydrogen element is 0 to 250, and d is 0.4D to 0.6D. The second direction is parallel to the first direction and opposite in direction.

5. The solar cell according to claim 1, characterized in that, Along the first direction, the slope of the signal intensity of hydrogen in the second passivation layer is -180 to -240.

6. The solar cell according to claim 1, characterized in that, Within a region extending 0-1 μm from the first surface and / or the second surface of the semiconductor substrate along the first direction, the relative intensity of the hydrogen element decreases along the first direction.

7. The solar cell according to claim 6, characterized in that, Within a region of 0~0.5μm thickness extending along the first direction from the first surface and / or second surface of the semiconductor substrate, the slope of the relative intensity of the hydrogen element is -120~-50; and / or Within a region with a thickness of 0.5 μm to 1 μm extending along the first direction from the first surface and / or the second surface of the semiconductor substrate, the slope of the relative intensity of the hydrogen element is -50 to -5.

8. The solar cell according to claim 1, characterized in that, The refractive index of the first passivation layer is greater than that of the second passivation layer.

9. The solar cell according to claim 8, characterized in that, The refractive index of the first passivation layer is 1.8 to 2.3; and / or the refractive index of the second passivation layer is 1.0 to 1.

7.

10. The solar cell according to claim 1, characterized in that, The thickness difference between the first passivation layer and the second passivation layer is less than 100 nm.

11. The solar cell according to claim 1, characterized in that, The thickness of the first passivation layer is 20nm~150nm; and / or the thickness of the second passivation layer is 20nm~150nm.

12. A method for preparing a solar cell according to any one of claims 1 to 11, characterized in that, Includes the following steps: A semiconductor substrate is provided, the semiconductor substrate having a first surface and a second surface disposed opposite to each other; A first passivation layer is obtained by first deposition of the first gas on the first surface and / or the second surface using plasma-enhanced chemical vapor deposition. The second gas is deposited on the first surface and / or the second surface using plasma-enhanced chemical vapor deposition to obtain a second passivation layer. The first gas and / or the second gas includes a gaseous silicon source and hydrogen, and the first gas and / or the second gas also includes at least one of a gaseous oxygen source and a gaseous nitrogen source, and the temperature of the first deposition and / or the second deposition is 350°C to 440°C.

13. The preparation method according to claim 12, characterized in that, The hydrogen flow rate is 200 sccm to 30000 sccm.

14. The preparation method according to claim 12, characterized in that, The temperature difference between the first deposition and the second deposition is less than 30°C.

15. A photovoltaic module, characterized in that, The photovoltaic module includes: A battery string, wherein the battery string is formed by connecting multiple solar cells as described in any one of claims 1 to 11 or solar cells prepared by the preparation method described in any one of claims 12 to 14; An encapsulation layer that covers the surface of the battery string; A cover plate for covering the surface of the encapsulation layer away from the battery string.

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